NOISE CANCELLATION TECHNOLOGIES INC
8-K, 1997-03-25
MISCELLANEOUS ELECTRICAL MACHINERY, EQUIPMENT & SUPPLIES
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                                1



                SECURITIES AND EXCHANGE COMMISSION
                      Washington, D.C. 20549



                             FORM 8-K



                          CURRENT REPORT


                Pursuant to Section 13 or 15(d) of
               the Securities Exchange Act of 1934


Date of Report (Date of earliest event reported): March 11 , 1997
- ------------------------------------------------------------------

              Noise Cancellation Technologies, Inc.
- ------------------------------------------------------------------
        (Exact name of Registrant as specified in Charter)


     Delaware                   0-18267                  59-2501025
(State or other juris-          (Commission              (IRS Employer
diction of incorporation)       File Number)             Identification
                                                         Number)

1025 West Nursery Road, Suite 120, Linthicum, Maryland   2 1 0 9 0
(Address of principal executive offices)                 (Zip Code)

Registrant's telephone number including area code:       (410) 636-8700


                               None
- ------------------------------------------------------------------
  (Former name or former address, if changes since last report)




<PAGE>
 




 Item 7.    Exhibits

                                                              Sequential
Exhibit No. Description                                          Page

1(a)        Agreement dated December 10, 1996, between
            Noise Cancellation Technologies, Inc. and
            Schwebel Capital Investments, Inc. incorporated
            by reference to Exhibit 1(a) of Registrant's
            Report on Form 8-K filed on January 27, 1997.

1(b)        Agreement dated December 10, 1996, between
            Noise Cancellation Technologies, Inc. and
            Alexander Wescott and Co., Inc. incorporated
            by reference to Exhibit 1(b) of Registrant's
            Report on Form 8-K filed on January 27, 1997.

1(c)        Agreement dated February 21, 1997, between
            Noise Cancellation Technologies, Inc. and
            VenGua Capital Markets Ltd.

4(a)        Form of Noise Cancellation Technologies, Inc.
            8% Convertible Debenture due March 11, 2000.
            Issued on March 11, 1997, to UFH Endowment Ltd.

4(b)        Form of Noise Cancellation Technologies, Inc.
            8% Convertible Debenture due March 11, 2000.
            Issued on March 11, 1997, to Austost Anstalt Schaan.

4(c)        Form of Noise Cancellation Technologies, Inc.
            8% Convertible Debenture due March 12, 2000.
            Issued on March 12, 1997, to Optimum Fund.

4(d)        Form of Noise Cancellation Technologies, Inc.
            8% Convertible Debenture due March 14, 2000.
            Issued on March 14, 1997, to Sage Capital
            Investments Limited.

4(e)        Form of Noise Cancellation Technologies, Inc.
            8% Convertible Debenture due March 25, 2000.
            Issued on March 25, 1997, to Optimum Fund.




<PAGE>


Item 9.     Sales of Equity Securities Pursuant to Regulation S

FIRST SALE

(a) March 11, 1997.  Eight  Percent  (8%)  Non-Voting  Subordinated  Convertible
Debentures  Due March 11, 2000,  each in the principal  amount of fifty thousand
dollars  ($50,000.00)  (the  "Debentures").  Aggregate  principal  amount of two
hundred fifty thousand dollars ($250,000.00).

(b) Name of placement agents - VenGua Capital Markets Ltd. Identity of person to
which  the  Registrant  sold  the  Debentures   -UFH  Endowment   Ltd.,   Vadux,
Liechtenstein (the "Purchaser").

(c) Total  offering price - two hundred fifty  thousand  dollars  ($250,000.00).
Total commissions - twenty-five thousand dollars ($25,000.00).

(d) Exemption from registration claimed under Regulation S promulgated under the
Securities Act of 1933, as amended (respectively, "Regulation S" and the "Act").
To the best of the  Registrant's  knowledge  and belief and in  accordance  with
representations  and  warranties  made by the Purchaser of the  Debentures,  the
Purchaser is not a "U.S.  Person" as defined under  Regulation S, the Registrant
did not engage in any "directed  selling  efforts" as defined under Regulation S
in connection  with the offer or sale of the  Debentures and said offer and sale
complied in all other  respects with the  provisions of Regulation S required to
permit the sale of the Debentures by the Registrant  without compliance with the
registration requirements of the Act.

(e) The  holder  of the  Debentures  is  entitled,  at its  option,  at any time
commencing  on or after  forty-five  (45)  days  after the  closing  date of the
purchase  thereof  (the  "Closing  Date") to convert the full  unpaid  principal
amount of the  Debentures  into shares of Common  Stock of the  Registrant  (the
"Conversion  Shares") at a conversion  price (the  "Conversion  Price") for each
Conversion Share equal to the lesser of eighty-five percent (85%) of the closing
bid of the Common Stock on the Closing Date or seventy-five percent (75%) of the
average  closing bid price of the Common  Stock for the five (5) NASDAQ  trading
days  immediately  preceding  the date of conversion as reported by the National
Association of Securities Dealers Automated Quotation System; provided, however,
that in no event shall the  Conversion  Price ever be less than $0.18 per share.
The number of Conversion Shares to be received by the holder on conversion shall
be the product of the unpaid  principal amount of the Debentures being converted
divided by the Conversion  Price.  The Registrant may, at its own option,  cause
the  automatic  conversion  into  Conversion  Shares  of all or any  part of the
Debentures  after  February  15, 1998 at the  aforesaid  Conversion  Price.  The
Registrant  may exercise  its option to cause the  automatic  conversion  as set
forth herein after sixty (60) days notice to the holder  during which sixty (60)
days  the  holder  may  convert  in  accordance  with  the  holder's  conversion
privileges.  After  the  sixty  (60)  days and the  exercise  of said  automatic
conversion,  Registrant may only exercise  further  automatic  conversion(s)  in
connection  with not less than  twenty-five  percent (25%) of the then remaining
amounts of outstanding  Conversion  Shares  pertaining to all of the unconverted
Debentures  per automatic  conversion  and only after thirty (30) days notice to
the holder  during which  thirty (30) days the holder may convert in  accordance
with the  holder's  conversion  privileges.  Payment  of each  interest  payment
payable under the Debentures may, at the Registrant's option, be made in cash or
by delivery of shares of the Registrant's  Common Stock. The number of shares to
be delivered shall be based on one hundred percent (100%) of the average closing
bid price of the  Registrant's  Common  Stock as reported on NASDAQ for the Five
(5) Trading Days immediately preceding the record date for the interest payment.

SECOND SALE

(a) March 11, 1997.  Eight  Percent  (8%)  Non-Voting  Subordinated  Convertible
Debentures  Due March 11, 2000,  each in the principal  amount of fifty thousand
dollars  ($50,000.00)  (the  "Debentures").  Aggregate  principal  amount of two
hundred fifty thousand dollars ($250,000.00).

(b) Name of placement agents - VenGua Capital Markets Ltd. Identity of person to
which the  Registrant  sold the  Debentures  -Austost  Anstalt  Schaan,  Schaan,
Liechtenstein (the "Purchaser").

(c) Total  offering price - two hundred fifty  thousand  dollars  ($250,000.00).
Total commissions - twenty-five thousand dollars ($25,000.00).

(d) Exemption from registration claimed under Regulation S promulgated under the
Securities Act of 1933, as amended (respectively, "Regulation S" and the "Act").
To the best of the  Registrant's  knowledge  and belief and in  accordance  with
representations  and  warranties  made by the Purchaser of the  Debentures,  the
Purchaser is not a "U.S.  Person" as defined under  Regulation S, the Registrant
did not engage in any "directed  selling  efforts" as defined under Regulation S
in connection  with the offer or sale of the  Debentures and said offer and sale
complied in all other  respects with the  provisions of Regulation S required to
permit the sale of the Debentures by the Registrant  without compliance with the
registration requirements of the Act.

(e) The  holder  of the  Debentures  is  entitled,  at its  option,  at any time
commencing  on or after  forty-five  (45)  days  after the  closing  date of the
purchase  thereof  (the  "Closing  Date") to convert the full  unpaid  principal
amount of the  Debentures  into shares of Common  Stock of the  Registrant  (the
"Conversion  Shares") at a conversion  price (the  "Conversion  Price") for each
Conversion Share equal to the lesser of eighty-five percent (85%) of the closing
bid of the Common Stock on the Closing Date or seventy-five percent (75%) of the
average  closing bid price of the Common  Stock for the five (5) NASDAQ  trading
days  immediately  preceding  the date of conversion as reported by the National
Association of Securities Dealers Automated Quotation System; provided, however,
that in no event shall the  Conversion  Price ever be less than $0.18 per share.
The number of Conversion Shares to be received by the holder on conversion shall
be the product of the unpaid  principal amount of the Debentures being converted
divided by the Conversion  Price.  The Registrant may, at its own option,  cause
the  automatic  conversion  into  Conversion  Shares  of all or any  part of the
Debentures  after  February  15, 1998 at the  aforesaid  Conversion  Price.  The
Registrant  may exercise  its option to cause the  automatic  conversion  as set
forth herein after sixty (60) days notice to the holder  during which sixty (60)
days  the  holder  may  convert  in  accordance  with  the  holder's  conversion
privileges.  After  the  sixty  (60)  days and the  exercise  of said  automatic
conversion,  Registrant may only exercise  further  automatic  conversion(s)  in
connection  with not less than  twenty-five  percent (25%) of the then remaining
amounts of outstanding  Conversion  Shares  pertaining to all of the unconverted
Debentures  per automatic  conversion  and only after thirty (30) days notice to
the holder  during which  thirty (30) days the holder may convert in  accordance
with the  holder's  conversion  privileges.  Payment  of each  interest  payment
payable under the Debentures may, at the Registrant's option, be made in cash or
by delivery of shares of the Registrant's  Common Stock. The number of shares to
be delivered shall be based on one hundred percent (100%) of the average closing
bid price of the  Registrant's  Common  Stock as reported on NASDAQ for the Five
(5) Trading Days immediately preceding the record date for the interest payment.

THIRD SALE

(a) March 12, 1997.  Eight  Percent  (8%)  Non-Voting  Subordinated  Convertible
Debentures  Due March 12, 2000,  each in the principal  amount of fifty thousand
dollars  ($50,000.00)  (the  "Debentures").  Aggregate  principal  amount of one
hundred thousand dollars ($100,000.00).

(b)   Name of placement agents - Alexander, Wescott & Co., Inc.
and Schwebel Capital Investments, Inc.  Identity of person to
which the Registrant sold the Debentures - Optimum Fund,
Georgetown, Grand Cayman, Grand Cayman Island, British Virgin
Islands (the "Purchaser").

(c) Total offering price - one hundred  thousand  dollars  ($100,000.00).  Total
commissions - eleven thousand dollars ($11,000.00).

(d) Exemption from registration claimed under Regulation S promulgated under the
Securities Act of 1933, as amended (respectively, "Regulation S" and the "Act").
To the best of the  Registrant's  knowledge  and belief and in  accordance  with
representations  and  warranties  made by the Purchaser of the  Debentures,  the
Purchaser is not a "U.S.  Person" as defined under  Regulation S, the Registrant
did not engage in any "directed  selling  efforts" as defined under Regulation S
in connection  with the offer or sale of the  Debentures and said offer and sale
complied in all other  respects with the  provisions of Regulation S required to
permit the sale of the Debentures by the Registrant  without compliance with the
registration requirements of the Act.

(e) The  holder  of the  Debentures  is  entitled,  at its  option,  at any time
commencing  on or after  forty-five  (45)  days  after the  closing  date of the
purchase  thereof  (the  "Closing  Date") to convert the full  unpaid  principal
amount of the  Debentures  into shares of Common  Stock of the  Registrant  (the
"Conversion  Shares") at a conversion  price (the  "Conversion  Price") for each
Conversion Share equal to the lesser of eighty-five percent (85%) of the closing
bid of the Common  Stock on the  Closing  Date or seventy  percent  (70%) of the
average  closing bid price of the Common  Stock for the five (5) NASDAQ  trading
days  immediately  preceding  the date of conversion as reported by the National
Association of Securities Dealers Automated Quotation System; provided, however,
that in no event shall the  Conversion  Price ever be less than $0.23 per share.
The number of Conversion Shares to be received by the holder on conversion shall
be the product of the unpaid  principal amount of the Debentures being converted
divided by the Conversion  Price.  The Registrant may, at its own option,  cause
the  automatic  conversion  into  Conversion  Shares  of all or any  part of the
Debentures  after  February  15, 1998 at the  aforesaid  Conversion  Price.  The
Registrant  may exercise  its option to cause the  automatic  conversion  as set
forth herein after sixty (60) days notice to the holder  during which sixty (60)
days  the  holder  may  convert  in  accordance  with  the  holder's  conversion
privileges.  After  the  sixty  (60)  days and the  exercise  of said  automatic
conversion,  Registrant may only exercise  further  automatic  conversion(s)  in
connection  with not less than  twenty-five  percent (25%) of the then remaining
amounts of outstanding  Conversion  Shares  pertaining to all of the unconverted
Debentures  per automatic  conversion  and only after thirty (30) days notice to
the holder  during which  thirty (30) days the holder may convert in  accordance
with the  holder's  conversion  privileges.  Payment  of each  interest  payment
payable under the Debentures may, at the Registrant's option, be made in cash or
by delivery of shares of the Registrant's  Common Stock. The number of shares to
be delivered shall be based on one hundred percent (100%) of the average closing
bid price of the  Registrant's  Common  Stock as reported on NASDAQ for the Five
(5) Trading Days immediately preceding the record date for the interest payment.

FOURTH SALE

(a) March 14, 1997.  Eight  Percent  (8%)  Non-Voting  Subordinated  Convertible
Debentures  Due March 14, 2000,  each in the principal  amount of fifty thousand
dollars  ($50,000.00)  (the  "Debentures").  Aggregate  principal  amount of one
hundred fifty thousand dollars ($150,000.00).

(b)   Name of placement agents - Alexander, Wescott & Co., Inc.
and Schwebel Capital Investments, Inc.  Identity of person to
which the Registrant sold the Debentures - Sage Capital
Investments Limited, Nassau, Bahamas (the "Purchaser").

(c) Total  offering price - one hundred fifty  thousand  dollars  ($150,000.00).
Total commissions - sixteen thousand five hundred dollars ($16,500.00).

(d) Exemption from registration claimed under Regulation S promulgated under the
Securities Act of 1933, as amended (respectively, "Regulation S" and the "Act").
To the best of the  Registrant's  knowledge  and belief and in  accordance  with
representations  and  warranties  made by the Purchaser of the  Debentures,  the
Purchaser is not a "U.S.  Person" as defined under  Regulation S, the Registrant
did not engage in any "directed  selling  efforts" as defined under Regulation S
in connection  with the offer or sale of the  Debentures and said offer and sale
complied in all other  respects with the  provisions of Regulation S required to
permit the sale of the Debentures by the Registrant  without compliance with the
registration requirements of the Act.

(e) The  holder  of the  Debentures  is  entitled,  at its  option,  at any time
commencing  on or after  forty-five  (45)  days  after the  closing  date of the
purchase  thereof  (the  "Closing  Date") to convert the full  unpaid  principal
amount of the  Debentures  into shares of Common  Stock of the  Registrant  (the
"Conversion  Shares") at a conversion  price (the  "Conversion  Price") for each
Conversion Share equal to the lesser of eighty-five percent (85%) of the closing
bid of the Common  Stock on the  Closing  Date or seventy  percent  (70%) of the
average  closing bid price of the Common  Stock for the five (5) NASDAQ  trading
days  immediately  preceding  the date of conversion as reported by the National
Association of Securities Dealers Automated Quotation System; provided, however,
that in no event shall the  Conversion  Price ever be less than $0.23 per share.
The number of Conversion Shares to be received by the holder on conversion shall
be the product of the unpaid  principal amount of the Debentures being converted
divided by the Conversion  Price.  The Registrant may, at its own option,  cause
the  automatic  conversion  into  Conversion  Shares  of all or any  part of the
Debentures  after  February  15, 1998 at the  aforesaid  Conversion  Price.  The
Registrant  may exercise  its option to cause the  automatic  conversion  as set
forth herein after sixty (60) days notice to the holder  during which sixty (60)
days  the  holder  may  convert  in  accordance  with  the  holder's  conversion
privileges.  After  the  sixty  (60)  days and the  exercise  of said  automatic
conversion,  Registrant may only exercise  further  automatic  conversion(s)  in
connection  with not less than  twenty-five  percent (25%) of the then remaining
amounts of outstanding  Conversion  Shares  pertaining to all of the unconverted
Debentures  per automatic  conversion  and only after thirty (30) days notice to
the holder  during which  thirty (30) days the holder may convert in  accordance
with the  holder's  conversion  privileges.  Payment  of each  interest  payment
payable under the Debentures may, at the Registrant's option, be made in cash or
by delivery of shares of the Registrant's  Common Stock. The number of shares to
be delivered shall be based on one hundred percent (100%) of the average closing
bid price of the  Registrant's  Common  Stock as reported on NASDAQ for the Five
(5) Trading Days immediately preceding the record date for the interest payment.

FIFTH SALE

(a) March 25, 1997.  Eight  Percent  (8%)  Non-Voting  Subordinated  Convertible
Debentures  Due March 25, 2000,  each in the principal  amount of fifty thousand
dollars  ($50,000.00)  (the  "Debentures").  Aggregate  principal amount of five
hundred thousand dollars ($500,000.00).

(b) Name of placement agents - Schwebel Capital  Investments,  Inc.  Identity of
person to which the Registrant  sold the Debentures - Optimum Fund,  Georgetown,
Grand Cayman, Grand Cayman Island, British Virgin Islands (the "Purchaser").

(c) Total offering price - five hundred  thousand dollars  ($500,000.00).  Total
commissions - fifty-five thousand dollars ($55,000.00).

(d) Exemption from registration claimed under Regulation S promulgated under the
Securities Act of 1933, as amended (respectively, "Regulation S" and the "Act").
To the best of the  Registrant's  knowledge  and belief and in  accordance  with
representations  and  warranties  made by the Purchaser of the  Debentures,  the
Purchaser is not a "U.S.  Person" as defined under  Regulation S, the Registrant
did not engage in any "directed  selling  efforts" as defined under Regulation S
in connection  with the offer or sale of the  Debentures and said offer and sale
complied in all other  respects with the  provisions of Regulation S required to
permit the sale of the Debentures by the Registrant  without compliance with the
registration requirements of the Act.

(e) The  holder  of the  Debentures  is  entitled,  at its  option,  at any time
commencing  on or after  forty-five  (45)  days  after the  closing  date of the
purchase  thereof  (the  "Closing  Date") to convert the full  unpaid  principal
amount of the  Debentures  into shares of Common  Stock of the  Registrant  (the
"Conversion  Shares") at a conversion  price (the  "Conversion  Price") for each
Conversion Share equal to the lesser of eighty-five percent (85%) of the closing
bid of the Common  Stock on the  Closing  Date or seventy  percent  (70%) of the
average  closing bid price of the Common  Stock for the five (5) NASDAQ  trading
days  immediately  preceding  the date of conversion as reported by the National
Association of Securities Dealers Automated Quotation System; provided, however,
that in no event shall the  Conversion  Price ever be less than $0.23 per share.
The number of Conversion Shares to be received by the holder on conversion shall
be the product of the unpaid  principal amount of the Debentures being converted
divided by the Conversion  Price.  The Registrant may, at its own option,  cause
the  automatic  conversion  into  Conversion  Shares  of all or any  part of the
Debentures  after  February  15, 1998 at the  aforesaid  Conversion  Price.  The
Registrant  may exercise  its option to cause the  automatic  conversion  as set
forth herein after sixty (60) days notice to the holder  during which sixty (60)
days  the  holder  may  convert  in  accordance  with  the  holder's  conversion
privileges.  After  the  sixty  (60)  days and the  exercise  of said  automatic
conversion,  Registrant may only exercise  further  automatic  conversion(s)  in
connection  with not less than  twenty-five  percent (25%) of the then remaining
amounts of outstanding  Conversion  Shares  pertaining to all of the unconverted
Debentures  per automatic  conversion  and only after thirty (30) days notice to
the holder  during which  thirty (30) days the holder may convert in  accordance
with the  holder's  conversion  privileges.  Payment  of each  interest  payment
payable under the Debentures may, at the Registrant's option, be made in cash or
by delivery of shares of the Registrant's  Common Stock. The number of shares to
be delivered shall be based on one hundred percent (100%) of the average closing
bid price of the  Registrant's  Common  Stock as reported on NASDAQ for the Five
(5) Trading Days immediately preceding the record date for the interest payment.




<PAGE>


                            SIGNATURES


      Pursuant to the  requirements of the Securities  Exchange Act of 1934, the
registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
undersigned hereunto duly authorized.

                  NOISE CANCELLATION TECHNOLOGIES, INC.


                  By:  /s/ STEPHEN J. FOGARTY
                       --------------------------------
                       Stephen J. Fogarty
                       Senior Vice President and
                       Chief Financial Officer

Dated:  March 25, 1997







<PAGE>

- --------------------------------------------------------------------------------
21
- --------------------------------------------------------------------------------

EXHIBIT 1(c)

                               Amended Term Sheet
                  Between Noise Cancellation Technologies, Inc.
                         and VenGua Capital Markets Ltd.
                               21st February 1997

Amount            Up to $1,000,000 (one million) USD closing in
increments.

Placement Fee     10% (ten percent).

Coupon            8% per annum (cash or stock) at the company's
discretion.

Type              Convertible Debenture, maturing in 2 (two) years and
convertible
                  any time after 45 (forty-five) days.

Conversion Price  At the lower of 15% under the bid on the day of subscription
or, 25%
                  under the bid on the day of conversion (using the five day
average).
                  However, in no event shall the conversion price be less than
18 cents per
                  share, as provided in the subscription agreement.

Condition         Mutual agreement on the specific details of the investment.
The investors
                  receiving Investor Packs with latest 10K and 10Q's.

Closing           Will close within seven (7) days.

The parties  hereby  acknowledge  their mutual  agreement to the above terms and
their intention to negotiate the contemplated transaction in an expedited manner
and in good faith. This term sheet represents our current agreement with respect
to the subject matter hereof and supersedes any prior agreement or understanding
with the respect of such subject  matter.  If this term sheet is not executed by
both parties at the close of business on the 28th  February  1997 then this term
sheet will be considered  void.  By executing the term sheet Noise  Cancellation
Technologies  Inc.  represents and warrants that it has obtained or within seven
(7) calendar  days will obtain the  necessary,  Board of directors  and/or other
approvals to cause this term sheet to be duly authorised, executed and delivered
by Noise Cancellation Technologies, Inc.

Agreed and Accepted by:

                  Company: NCT, Inc.

                  Officer: /s/ STEPHEN J. FOGARTY, CFO (Title)

                           Date: 2/21/97


                           VenGua Capital Markets Limited

                           /s/ KEITH BEASLEY

                           Date: 21/2/97




<PAGE>


EXHIBIT 4(a)

No. ___
USD$50,000.00


                      NOISE CANCELLATION TECHNOLOGIES, INC.


                  8% CONVERTIBLE DEBENTURE DUE MARCH 11, 2000


THE DEBENTURE  REPRESENTED BY THIS CERTIFICATE AND THE SECURITIES  ISSUABLE UPON
CONVERSION  HEREOF HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED.  THE  DEBENTURE  HAS BEEN  ACQUIRED  FOR  INVESTMENT  AND NEITHER  THIS
DEBENTURE  NOR THE  SECURITIES  ISSUABLE  UPON  CONVERSION  HEREOF  MAY BE SOLD,
TRANSFERRED  OR ASSIGNED IN THE ABSENCE OF AN EFFECTIVE  REGISTRATION  STATEMENT
FOR THE DEBENTURE OR SUCH  SECURITIES,  AS THE CASE MAY BE, UNDER THE SECURITIES
ACT OF 1933, AS AMENDED,  UNLESS SOLD PURSUANT TO RULE 144 UNDER SAID ACT, OR BY
MEANS OF  ANOTHER  SALE NOT  REQUIRING  REGISTRATION  OF THE  DEBENTURE  OR SUCH
SECURITIES  UNDER SAID ACT.  ANY SUCH SALE,  ASSIGNMENT  OR  TRANSFER  MUST ALSO
COMPLY WITH APPLICABLE STATE SECURITIES LAW.


THIS DEBENTURE is one of a duly authorized  issue (the "Issue") of Debentures of
NOISE CANCELLATION TECHNOLOGIES, INC., a corporation duly organized and existing
under the laws of the State of Delaware (the  "Issuer")  designated as its Eight
Percent (8%) Non-Voting Subordinated  Convertible Debentures due MARCH 11, 2000,
in an aggregate principal amount of Two Hundred Fifty Thousand
United States Dollars (USD$250,000.00).

FOR VALUE RECEIVED, the Issuer promises to pay to

                   UFH ENDOWMENT LTD.
                   C/O UNIVERSAL FINANZ HOLDING AG
                   DRESCHEWEG 2, POSTFACH 828
                   FL-9490 VADUX / LIECHTENSTEIN

the  registered  holder hereof and its  successors  and assigns (the  "Holder"),
the principal sum of

                                 FIFTY THOUSAND
                      UNITED STATES DOLLARS (USD$50,000.00)

                                       on
                                 March 11, 2000
                             (the "Maturity Date"),




<PAGE>



and to pay  interest  on the  principal  sum  outstanding  at the  rate of Eight
Percent (8%) per annum due and payable on March 31st, June 30th,  September 30th
and December 31st of each year until maturity. Interest shall begin to accrue on
the closing date applicable to the issuance of this Debenture as provided in the
"Subscription  Agreement"  defined below (the "Closing  Date").  Payment of each
interest payment may, at the Issuer's option,  be made in cash or by delivery of
the  shares of the  Issuer's  Common  Stock  ("Common  Stock").  In the event an
interest  payment  is made in shares of Common  Stock,  the  number of shares of
Common Stock to be delivered shall be based on one hundred percent (100%) of the
average  closing bid price of the  Issuer's  Common  Stock as reported on NASDAQ
(or,  if not quoted on NASDAQ,  as reported  by any other  recognized  quotation
system  on which  the  price of the  Common  Stock is  quoted)  for the Five (5)
Trading Days immediately  preceding the record date for the interest payment. No
fractional  shares or scrip  representing  fraction shares will be issued for an
interest  payment,  but the  number of shares  issuable  shall be rounded to the
nearest whole share. The interest so payable will be paid to the person in whose
name  this  Debenture  is  registered  on the  record  of the  Issuer  regarding
registration  and  transfers  of  the  Debenture  (the  "Debenture   Register");
provided,  however,  that  the  Issuer's  obligation  to a  transferee  of  this
Debenture  arises only if such  transfer,  sale or other  disposition is made in
accordance  with the terms and conditions of the Offshore  Debenture  Securities
Subscription Agreement dated as of March 11, 1997, or such other mutually agreed
to date, between the Issuer and the Holder (the "Subscription  Agreement").  The
principal  of, and  interest  of this  Debenture  (to the extent not  payable by
delivery  of  shares  of  Issuer's  Common  Stock in  accordance  with the terms
thereof) are payable in such coin or currency of the United States of America as
at the time of payment is legal tender for payment of public and private  debts,
at the  address  last  appearing  on the  debenture  Register  of the  Issuer as
designated  in writing by the Holder  hereof from time to time.  The Issuer will
pay the principal of and accrued and unpaid  interest due upon this debenture on
the Maturity Date, less any amounts  required by law to be deducted or withheld,
to the Holder at the last address on the Debenture Register. The receipt of such
check or shares of Common  Stock shall  constitute  a payment of  principal  and
interest  hereunder  and shall satisfy and discharge the liability for principal
and  interest on this  Debenture  to the extent of the sum  represented  by such
check or shares of Common Stock plus any amounts so deducted.

This Debenture is subject to the following additional provisions:

1.    The Debentures  are issuable in  denominations  of Fifty  Thousand  United
      States Dollars (USD$50,000.00).

2.    The Issuer  shall be entitled to withhold  from all  payments of principal
      of, and interest on, this Debenture any amounts required to withheld under
      the  applicable  provisions  of the  United  States  income  tax or  other
      applicable laws at the time of such payments.
3.    This   Debenture  has  been  issued   subject  to  investment   and  other
      representations  of  the  original  Holder  hereof  as  set  forth  in the
      Subscription  Agreement and may be  transferred or exchanged in the United
      States only in  compliance  with the  Securities  Act of 1933,  as amended
      (the  "Act")  and  applicable  state  securities  laws.  Prior  to the due
      presentment  for such  transfer  of this  Debenture,  the  Issuer  and any
      agent of the Issuer may treat the person in whose name this  Debenture  is
      duly  registered  on the Issuer's  Debenture  Register as the owner hereof
      for the purpose of receiving  payment as provided and all other  purposes,
      whether or not this  Debenture be overdue,  and neither the Issuer nor any
      agent shall be affected by notice to contrary.

4.    The  Holder  of  this  Debenture  is  entitled,  at  its  option,  at  any
      time  commencing  on or after  forty-five  (45)  days  after  the  Closing
      Date to convert the full unpaid  principal  amount of this  Debenture into
      shares  of Common  Stock of the  Issuer  (the  "Conversion  Shares")  at a
      conversion  price  (the  "Conversion  Price")  for each  Conversion  Share
      equal to the lesser of  eighty-five  percent  (85%) of the  closing bid of
      the Common  Stock on the Closing  Date or  seventy-five  percent  (75%) of
      the  average  closing  bid  price  of the  Common  Stock  for the five (5)
      NASDAQ  Trading  Days  immediately   preceding  the  Conversion  Date  (as
      hereinafter   defined),   as  reported  by  the  National  Association  of
      Securities  Dealers  Automated  Quotation  System  (or,  if not  quoted on
      NASDAQ,  as reported  by any other  recognized  quotation  system on which
      the price of the Common Stock is quoted).  Provided,  however,  that in no
      event  shall  the  Conversion  Price  ever be less than  $0.18 per  share.
      The number of  Conversion  Shares to be received  by Holder on  conversion
      shall be the  product  of the  unpaid  principal  amount of the  Debenture
      being  converted  divided by the Conversion  Price. On the Closing Date as
      defined in the  Subscription  Agreement,  the Issuer  will  reserve on its
      books one hundred  eighty-seven  thousand five hundred (187,500) shares of
      Common  Stock  for  use  in  connection   with  the   conversion  of  this
      Debenture.  The Issuer  does  hereby  irrevocably  agree to  instruct  its
      Transfer   Agent  to  provide  Common  Stock   Certificates   representing
      Conversion   Shares  to  the  Holder  in  accordance  with  the  terms  of
      conversion  hereinafter  set out.  Holder  shall  not sell any  Conversion
      Shares so converted  until  forty-five  (45) days after the Closing  Date.
      Such   conversion   by  the  Holder   shall  be  effected  by  the  Holder
      surrendering  to the Issuer  this  Debenture  with the form of  Conversion
      Notice  attached  hereto as  Exhibit  1,  executed  by the  Holder of this
      Debenture  and  accompanied,   if  required  by  the  Issuer,   by  proper
      assignment  hereof in blank  delivered  in the manner  and time  period as
      hereinafter  set out.  The Issuer shall then  instruct its Transfer  Agent
      to deliver the  appropriate  Common Stock  Certificate to the Holder.  For
      purposes of this Debenture,  the  "Conversion  Date" shall be deemed to be
      the date on which  the  Holder  has sent by  facsimile  the  executed  and
      completed  Conversion  notice  together with a copy of this  Debenture and
      any  applicable  executed  assignment to the Issuer.  In order to convert,
      this  Debenture   together  with  the  Original   Conversion  Notice  duly
      executed,  must be delivered by express  courier to the Issuer  within Two
      (2) NASDAQ  Trading Days of the Conversion  Date.  The  Conversion  Shares
      must be  issued  and  returned  by the  Transfer  Agent to the  Holder  by
      express  courier with Five (5) NASDAQ  Trading  Days after the  Conversion
      Date.  Accrued  but unpaid  interest  shall,  at the option of the Issuer,
      be subject to conversion  under the terms and  conditions  concerning  the
      payment of  interest  set forth  above at the time of  conversion  of this
      Debenture  or at the time any  quarterly  interest  payments  are due.  No
      fractional shares or scrip  representing  fractional shares will be issued
      on conversion,  but the number of shares  issuable shall be rounded to the
      nearest  whole  share.  The  Issuer  may,  at its own  option,  cause  the
      automatic  conversion into Conversion  Shares of the full unpaid amount of
      this  Debenture  after  February  15,  1998  at the  aforesaid  Conversion
      Price.  The  Issuer  may  exercise  its  option  to  cause  the  automatic
      conversion  as set forth  herein  after  said  sixty  (60) days  notice to
      Holder  during  which  sixty (60) days  Holder may  convert in  accordance
      with  Holder's  conversion  privileges  hereunder.  After the  sixty  (60)
      days  and the  exercise  of said  automatic  conversion,  Issuer  may only
      exercise  further  automatic  conversion(s)  in  connection  with not less
      than  twenty-five   percent  (25%)  of  the  then  remaining   amounts  of
      outstanding  Conversion  Shares  pertaining  to  all  of  the  unconverted
      Debentures  of the Issue per  automatic  conversion  and only after thirty
      (30) days  notice to Holder  during  which  thirty  (30) days  Holder  may
      convert in  accordance  with  Holder's  conversion  privileges  hereunder.
      The  automatic  conversion  option shall be  effectively  exercised on the
      date on which the Issuer  transmits  by facsimile  transmission  and mails
      notice  of  said  conversion  to the  registered  Holder  of the  effected
      Debentures.  To effect  such  conversion  by the  Issuer,  the  Conversion
      Shares must be issued and  delivered by the  Transfer  Agent to the Holder
      by express  courier on or before the fifth (5th) NASDAQ  Trading Day after
      the last day of such sixty (60) or thirty (30) day notice  period,  as the
      case may be, or the date on which the  Holder  notifies  the  Issuer  that
      the Holder  elects not to  exercise  the  Holder's  conversion  privileges
      hereunder.  Upon  receipt of the  Conversion  Shares and the  payment  (in
      cash or Common  Stock as herein  provided)  of any  unpaid  interest,  the
      Holder shall immediately  deliver the Debenture,  appropriately  marked to
      indicate payment in full thereof,  to the Issuer or its assignee  pursuant
      to Issuer or its assignee's instructions.

5.    No provision of this Debenture shall alter or impair the obligation of the
      Issuer, which is absolute and unconditional,  to pay the principal of, and
      interest on, this Debenture at the place,  time and rate, and in the coins
      or currency, herein prescribed.
6.    The Issuer hereby  expressly  waives demand and  presentment  for payment,
      notice of  nonpayment,  protest,  notice of protest,  notice of  dishonor,
      notice  of  acceleration  or intent to  accelerate,  bringing  of suit and
      diligence  in taking any action to collect  amounts  called for  hereunder
      and shall be  directly  and  primarily  liable for the payment of all sums
      owing  and to be owing  hereon,  regardless  of and  without  any  notice,
      diligence,  act or omission as or with  respect to the  collection  of any
      amount called for hereunder.

7.    The  Issuer  agrees  to pay all cost and  expenses,  including  reasonable
      attorneys'  fees,  which may be incurred by the Holder in  collecting  any
      amount due or exercising the conversion rights under this Debenture.

8.    If one or  more of the  following  described  "Events  of  Default"  shall
      occur:

      (a)   The Issuer  shall  default in the payment of  principal  or interest
            on this Debenture; or

      (b)   Any of the  representations or warranties made by the Issuer herein,
            in the Subscription Agreement, or in any certificate or financial or
            other statements  heretofore or hereafter  furnished by or on behalf
            of the Issuer in connection  with the execution and delivery of this
            Debenture or the Subscription Agreement shall be false or misleading
            in any material respect at the time; or

      (c)   The Issuer shall fail to issue the  Conversion  Shares in accordance
            with  the  terms  of  conversion  set out in  Section  4 above or to
            perform or observe any other covenant,  term, provision,  condition,
            agreement or obligation of the Issuer under this  Debenture and such
            failure shall continue  uncured for a period of seven (7) days after
            notice from the Holder of such failure; or

      (d)   The Issuer  shall (1)  become  insolvent;  (2) admit in writing  its
            inability  to pay its debt  generally  as they  mature;  (3) make an
            assignment for the benefit of creditors or commence  proceedings for
            its dissolution; or (4) apply for or consent to the appointment of a
            trustee,  liquidator or receiver for it or for a substantial part of
            its property or business; or

      (e)   A trustee,  liquidator or receiver shall be appointed for the Issuer
            or a  substantial  part of its  property  or  business  without  its
            consent and shall not be  discharged  within  thirty (30) days after
            such appointment; or

      (f)   Any  governmental  agency or any court of competent  jurisdiction at
            the instance of any  governmental  agency  shall  assume  custody or
            control off the whole or any  substantial  portion of the properties
            or assets of the Issuer  and shall not be  dismissed  within  thirty
            (30) calendar days thereafter; or

      (g)   Bankruptcy,  reorganization,  insolvency or liquidation  proceedings
            or other  proceedings  for relief  under any  bankruptcy  law or any
            law for the  relief of  debtors  shall be  instituted  by or against
            the Issuer,  and if  instituted  against  the  Issuer,  shall not be
            dismissed  within thirty (30)  calendar days after such  institution
            or the Issuer  shall by any  action or answer  approve  of,  consent
            to, or  acquiesce  in any such  proceedings  or audit  the  material
            allegations  of, or default in  answering  a petition  filed in such
            proceeding; or

      (h)   The Issuer's Common Stock shall cease to be quoted on any of the New
            York  Stock  Exchange,  American  Stock  Exchange,   NASDAQ-National
            Market,  NASDAQ-Small  Cap or OTC  Electronic  Bulletin  Board for a
            period in excess of ninety (90) Calendar Days.

      Then, or at any time thereafter,  and in each and every such case,  unless
      such  Event of  Default  shall  have been  waived in writing by the Holder
      (which  waiver  shall  not be  deemed  to be a  waiver  of any  subsequent
      default) at the option of the Holder and in the Holder's sole  discretion,
      the  Holder may  consider  this  Debenture  immediately  due and  payable,
      without presentment,  demand,  protest or notice of any kind, all of which
      are  hereby  expressly  waived,  anything  herein  or in any note or other
      instruments contained to the contrary notwithstanding,  and the Holder may
      immediately,  and without  expiration of any period of grace,  enforce any
      and all of the Holder's  rights and remedies  provided herein or nay other
      rights or remedies afforded by law.

9.    No  recourse  shall be had for the  payment  of the  principal  of, or the
      interest on, this Debenture,  or for any claim based hereon,  or otherwise
      in respect  hereof,  against  any  incorporator,  shareholder,  officer or
      director,  as  such,  past,  present  or  future,  of  the  Issuer  or any
      successor  corporation,  whether by virtue of any constitution,  statue or
      rule  of  law,  or  by   enforcement  by  any  assessment  or  penalty  or
      otherwise,  all such liability being, by acceptance  hereof and as part of
      the consideration for the issue hereof expressly waived and released.

10.   The Holder of this Debenture,  by execution of the Subscription  Agreement
      and  acceptance  hereof agrees that this  Debenture is being  acquired for
      investment purposes and that such Holder will not offer, sell or otherwise
      dispose of this  debenture  or the shares of Common  Stock  issuable  upon
      conversion thereof except under  circumstances which shall not result in a
      violation of the Act or any applicable  State Blue Sky law or similar laws
      relating to the sale of securities.

11.   By  acceptance of this  Debenture,  the Holder hereby grants to the Issuer
      or its assignee the option ("Prepayment  Option"),  for a period beginning
      after  February 15, 1998 to repurchase all of the  outstanding  portion of
      the  Debenture  plus  accrued  interest,  after  sixty (60) days notice to
      Holder  during  which  sixty (60) days  Holder may  convert in  accordance
      with Holder's  conversion  privileges  hereunder.  The repurchase price of
      this  Debenture  (the  "Repurchase  Price")  shall be equal to One Hundred
      Five  Percent  (105%)  of  the  full  unpaid   principal   amount  of  the
      Debenture,   plus  accrued  interest  payable  in  cash.  This  Prepayment
      Option may be exercised by written  notice via  telecopy  transmission  to
      the Holder (with  written  notice to the  registered  address by overnight
      courier) after  February 15, 1998 and delivery of the Repurchase  Price to
      the  Holder on or before  the fifth  (5th)  NASDAQ  trading  day after the
      last day of such  sixty  (60) day  notice  period or the date on which the
      Holder  notifies  the Issuer that the Holder  elects not to  exercise  the
      Holder's  conversion  privileges  hereunder,  whichever  is  sooner.  Upon
      receipt of the  Repurchase  Price,  Holder shall  immediately  deliver the
      Debenture,  appropriately  marked to indicate payment in full thereof,  to
      the  Issuer  or its  assignee  pursuant  to  Issuer's  or  its  assignee's
      instructions.

12.   In  the  case  that  there  is any  outstanding  amount  of the  Debenture
      unconverted on March 11, 2000, the outstanding  unconverted portion of the
      Debenture  will  be  subject  to  automatic  conversion  pursuant  to  the
      provisions of the last four sentences in Section 4 hereunder.

13.   In case any  provision  of this  Debenture is held by a court of competent
      jurisdiction   to  be  excessive   in  scope  or   otherwise   invalid  or
      unenforceable  such  provision  shall be adjusted  rather than voided,  if
      possible, so that such is enforceable to the maximum extent possible,  and
      the  validity  and  enforceability  of the  remaining  provisions  of this
      debenture will not in any way be affected or impaired thereby.

14.   This Debenture and the agreements referred to in this Debenture constitute
      the full and entire understanding and agreement between the Issuer and the
      Holder with respect  hereof.  Neither this  Debenture nor any terms hereof
      may be amended,  waived,  discharged or terminated other than by a written
      statement signed by the Issuer and the Holder.

15.   This Debenture  shall be governed by and construed in accordance  with the
      laws of the  state  of  Delaware  and the  United  State of  America.  Any
      judicial proceedings relating to the interpretation and performance of the
      terms and  conditions of this  Debenture  shall be conducted in such state
      and Federal  courts  located in the City,  County and State of New York as
      may be appropriate in each instance.


IN WITNESS  WHEREOF the Issuer has caused this instrument to be duly executed by
an officer thereunto duly authorized.

ISSUER:
NOISE CANCELLATION
TECHNOLOGIES, INC.



By:   /s/ STEPHEN J. FOGARTY
      Official Signatory of Issuer


Name (Printed:)   Stephen J. Fogarty

Title:            Senior Vice-President and Chief Financial Officer

Date              March 11, 1997



<PAGE>


                                    EXHIBIT 1
                              Notice of Conversion
  (To be executed by the Registered Holder in order to Convert the Debenture)

             TO:  Noise Cancellation Technologies, Inc.
                  One Dock Street
                  Stamford, Connecticut  06902
                  Attention:  John Horton, General Counsel
                  Fax:  (203) 348-4106
                  Tel:  (203) 961-0500 ext. 388

The  undersigned  (the  "Holder")  hereby  irrevocably  elects to convert  Fifty
Thousand  (USD  $50,000.00)  of  the  Debenture  No.___  of  NOISE  CANCELLATION
TECHNOLOGIES,  INC. (the "Issuer") according to the conditions set forth in such
Debenture,  as of the date  written  below.  The  shares are to be issued in the
"Street Name" written below:

The undersigned represents and warrants as follows:

(a)   The offer to convert the Debenture  was made to the Issuer  outside of the
      United States and the undersigned was, at the time the  subscription  form
      was executed and delivered, and is now outside the United States;

(b)   It is not a U.S.  person (as such term is  defined  in  Section  902(a) of
      Regulation  S  ("Regulation  S")  promulgated   under  the  United  States
      Securities Act of 1933 (the  "Securities  Act");  and it is converting the
      Debenture  for its own  account  and not for the account or benefit of any
      U.S. person;

(c)   All offers  and sales of the Common  Stock  shall be made  pursuant  to an
      effective  registration  statement under the Securities Act or pursuant to
      an exemption  from, or in a transaction  not subject to, the  registration
      requirements of the Securities Act;

(d)   It is  familiar  with  and  understands  the  terms  and  conditions,  and
      requirements  contained in Regulation S and  definitions  of U.S.  persons
      contained in Regulation S.

Holder:     UFH ENDOWMENT LTD.(seal)

By:         ____________________________
            Official Signatory of Holder

Title:      ____________________  Country of Execution:  Liechtenstein


<PAGE>


Conversion Date (See Section 4)                 ________________
Closing Bid on the Closing Date (See Section 4) ________________
Average Closing Bid Price (See Section 4)       ________________
Conversion Price (See Section 4)                ________________
Number of common shares to be
received by Holder (see Section 4)              ________________

Name of Holder for Registration                 ________________

Address for Registration                        ________________

                                                ________________

"Street Name" for certificate                   ________________



<PAGE>


EXHIBIT 4(b)

No. ___
USD$50,000.00


                      NOISE CANCELLATION TECHNOLOGIES, INC.


                  8% CONVERTIBLE DEBENTURE DUE MARCH 11, 2000


THE DEBENTURE  REPRESENTED BY THIS CERTIFICATE AND THE SECURITIES  ISSUABLE UPON
CONVERSION  HEREOF HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED.  THE  DEBENTURE  HAS BEEN  ACQUIRED  FOR  INVESTMENT  AND NEITHER  THIS
DEBENTURE  NOR THE  SECURITIES  ISSUABLE  UPON  CONVERSION  HEREOF  MAY BE SOLD,
TRANSFERRED  OR ASSIGNED IN THE ABSENCE OF AN EFFECTIVE  REGISTRATION  STATEMENT
FOR THE DEBENTURE OR SUCH  SECURITIES,  AS THE CASE MAY BE, UNDER THE SECURITIES
ACT OF 1933, AS AMENDED,  UNLESS SOLD PURSUANT TO RULE 144 UNDER SAID ACT, OR BY
MEANS OF  ANOTHER  SALE NOT  REQUIRING  REGISTRATION  OF THE  DEBENTURE  OR SUCH
SECURITIES  UNDER SAID ACT.  ANY SUCH SALE,  ASSIGNMENT  OR  TRANSFER  MUST ALSO
COMPLY WITH APPLICABLE STATE SECURITIES LAW.


THIS DEBENTURE is one of a duly authorized  issue (the "Issue") of Debentures of
NOISE CANCELLATION TECHNOLOGIES, INC., a corporation duly organized and existing
under the laws of the State of Delaware (the  "Issuer")  designated as its Eight
Percent (8%) Non-Voting Subordinated  Convertible Debentures due MARCH 11, 2000,
in an aggregate principal amount of Two Hundred Fifty Thousand
United States Dollars (USD$250,000.00).

FOR VALUE RECEIVED, the Issuer promises to pay to

                   AUSTOST ANSTALT SCHAAN
                   LIECHTENSTEIN SCHAAN

the  registered  holder hereof and its  successors  and assigns (the  "Holder"),
the principal sum of

                                 FIFTY THOUSAND
                      UNITED STATES DOLLARS (USD$50,000.00)

                                       on
                                 March 11, 2000
                             (the "Maturity Date"),




<PAGE>


and to pay  interest  on the  principal  sum  outstanding  at the  rate of Eight
Percent (8%) per annum due and payable on March 31st, June 30th,  September 30th
and December 31st of each year until maturity. Interest shall begin to accrue on
the closing date applicable to the issuance of this Debenture as provided in the
"Subscription  Agreement"  defined below (the "Closing  Date").  Payment of each
interest payment may, at the Issuer's option,  be made in cash or by delivery of
the  shares of the  Issuer's  Common  Stock  ("Common  Stock").  In the event an
interest  payment  is made in shares of Common  Stock,  the  number of shares of
Common Stock to be delivered shall be based on one hundred percent (100%) of the
average  closing bid price of the  Issuer's  Common  Stock as reported on NASDAQ
(or,  if not quoted on NASDAQ,  as reported  by any other  recognized  quotation
system  on which  the  price of the  Common  Stock is  quoted)  for the Five (5)
Trading Days immediately  preceding the record date for the interest payment. No
fractional  shares or scrip  representing  fraction shares will be issued for an
interest  payment,  but the  number of shares  issuable  shall be rounded to the
nearest whole share. The interest so payable will be paid to the person in whose
name  this  Debenture  is  registered  on the  record  of the  Issuer  regarding
registration  and  transfers  of  the  Debenture  (the  "Debenture   Register");
provided,  however,  that  the  Issuer's  obligation  to a  transferee  of  this
Debenture  arises only if such  transfer,  sale or other  disposition is made in
accordance  with the terms and conditions of the Offshore  Debenture  Securities
Subscription Agreement dated as of March 11, 1997, or such other mutually agreed
to date, between the Issuer and the Holder (the "Subscription  Agreement").  The
principal  of, and  interest  of this  Debenture  (to the extent not  payable by
delivery  of  shares  of  Issuer's  Common  Stock in  accordance  with the terms
thereof) are payable in such coin or currency of the United States of America as
at the time of payment is legal tender for payment of public and private  debts,
at the  address  last  appearing  on the  debenture  Register  of the  Issuer as
designated  in writing by the Holder  hereof from time to time.  The Issuer will
pay the principal of and accrued and unpaid  interest due upon this debenture on
the Maturity Date, less any amounts  required by law to be deducted or withheld,
to the Holder at the last address on the Debenture Register. The receipt of such
check or shares of Common  Stock shall  constitute  a payment of  principal  and
interest  hereunder  and shall satisfy and discharge the liability for principal
and  interest on this  Debenture  to the extent of the sum  represented  by such
check or shares of Common Stock plus any amounts so deducted.

This Debenture is subject to the following additional provisions:

1.    The Debentures  are issuable in  denominations  of Fifty  Thousand  United
      States Dollars (USD$50,000.00).

2.    The Issuer  shall be entitled to withhold  from all  payments of principal
      of, and interest on, this Debenture any amounts required to withheld under
      the  applicable  provisions  of the  United  States  income  tax or  other
      applicable laws at the time of such payments.

3.    This   Debenture  has  been  issued   subject  to  investment   and  other
      representations  of  the  original  Holder  hereof  as  set  forth  in the
      Subscription  Agreement and may be  transferred or exchanged in the United
      States only in  compliance  with the  Securities  Act of 1933,  as amended
      (the  "Act")  and  applicable  state  securities  laws.  Prior  to the due
      presentment  for such  transfer  of this  Debenture,  the  Issuer  and any
      agent of the Issuer may treat the person in whose name this  Debenture  is
      duly  registered  on the Issuer's  Debenture  Register as the owner hereof
      for the purpose of receiving  payment as provided and all other  purposes,
      whether or not this  Debenture be overdue,  and neither the Issuer nor any
      agent shall be affected by notice to contrary.

4.    The Holder of this  Debenture  is  entitled,  at its  option,  at any time
      commencing  on or after  forty-five  (45) days after the  Closing  Date to
      convert the full unpaid  principal  amount of this  Debenture  into shares
      of Common  Stock of the Issuer (the  "Conversion  Shares") at a conversion
      price (the  "Conversion  Price")  for each  Conversion  Share equal to the
      lesser of  eighty-five  percent  (85%) of the  closing  bid of the  Common
      Stock on the Closing  Date or  seventy-five  percent  (75%) of the average
      closing  bid price of the  Common  Stock for the five (5)  NASDAQ  Trading
      Days immediately  preceding the Conversion Date (as hereinafter  defined),
      as reported by the National  Association of Securities  Dealers  Automated
      Quotation  System (or,  if not quoted on NASDAQ,  as reported by any other
      recognized  quotation  system on which the  price of the  Common  Stock is
      quoted).  Provided,  however,  that in no event shall the Conversion Price
      ever be less than $0.18 per  share.  The  number of  Conversion  Shares to
      be  received  by Holder on  conversion  shall be the product of the unpaid
      principal  amount  of  the  Debenture  being  converted   divided  by  the
      Conversion  Price.  On the  Closing  Date as defined  in the  Subscription
      Agreement,  the Issuer will reserve on its books one hundred  eighty-seven
      thousand  five  hundred  (187,500)  shares  of  Common  Stock  for  use in
      connection  with  the  conversion  of  this  Debenture.  The  Issuer  does
      hereby  irrevocably  agree to  instruct  its  Transfer  Agent  to  provide
      Common Stock  Certificates  representing  Conversion  Shares to the Holder
      in accordance  with the terms of conversion  hereinafter  set out.  Holder
      shall not sell any Conversion  Shares so converted  until  forty-five (45)
      days after the  Closing  Date.  Such  conversion  by the  Holder  shall be
      effected  by the Holder  surrendering  to the Issuer this  Debenture  with
      the form of Conversion  Notice  attached  hereto as Exhibit 1, executed by
      the Holder of this Debenture and  accompanied,  if required by the Issuer,
      by proper  assignment  hereof in blank  delivered  in the  manner and time
      period  as  hereinafter  set out.  The  Issuer  shall  then  instruct  its
      Transfer  Agent to deliver the  appropriate  Common Stock  Certificate  to
      the  Holder.  For  purposes  of  this  Debenture,  the  "Conversion  Date"
      shall be deemed to be the date on which the Holder  has sent by  facsimile
      the executed  and  completed  Conversion  notice  together  with a copy of
      this Debenture and any applicable  executed  assignment to the Issuer.  In
      order to convert,  this  Debenture  together with the Original  Conversion
      Notice duly executed,  must be delivered by express  courier to the Issuer
      within  Two  (2)  NASDAQ  Trading  Days  of  the   Conversion   Date.  The
      Conversion  Shares must be issued and  returned by the  Transfer  Agent to
      the Holder by express  courier  with Five (5)  NASDAQ  Trading  Days after
      the Conversion  Date.  Accrued but unpaid  interest  shall,  at the option
      of the Issuer,  be subject to  conversion  under the terms and  conditions
      concerning  the  payment  of  interest  set  forth  above  at the  time of
      conversion  of  this  Debenture  or at the  time  any  quarterly  interest
      payments are due. No fractional  shares or scrip  representing  fractional
      shares  will be issued on  conversion,  but the number of shares  issuable
      shall be rounded to the nearest  whole  share.  The Issuer may, at its own
      option,  cause the  automatic  conversion  into  Conversion  Shares of the
      full  unpaid  amount of this  Debenture  after  February  15,  1998 at the
      aforesaid  Conversion  Price.  The Issuer may exercise its option to cause
      the  automatic  conversion  as set forth herein after said sixty (60) days
      notice to Holder  during  which  sixty  (60) days  Holder  may  convert in
      accordance  with  Holder's  conversion  privileges  hereunder.  After  the
      sixty (60) days and the  exercise  of said  automatic  conversion,  Issuer
      may only exercise further  automatic  conversion(s) in connection with not
      less than  twenty-five  percent  (25%) of the then  remaining  amounts  of
      outstanding  Conversion  Shares  pertaining  to  all  of  the  unconverted
      Debentures  of the Issue per  automatic  conversion  and only after thirty
      (30) days  notice to Holder  during  which  thirty  (30) days  Holder  may
      convert in  accordance  with  Holder's  conversion  privileges  hereunder.
      The  automatic  conversion  option shall be  effectively  exercised on the
      date on which the Issuer  transmits  by facsimile  transmission  and mails
      notice  of  said  conversion  to the  registered  Holder  of the  effected
      Debentures.  To effect  such  conversion  by the  Issuer,  the  Conversion
      Shares must be issued and  delivered by the  Transfer  Agent to the Holder
      by express  courier on or before the fifth (5th) NASDAQ  Trading Day after
      the last day of such sixty (60) or thirty (30) day notice  period,  as the
      case may be, or the date on which the  Holder  notifies  the  Issuer  that
      the Holder  elects not to  exercise  the  Holder's  conversion  privileges
      hereunder.  Upon  receipt of the  Conversion  Shares and the  payment  (in
      cash or Common  Stock as herein  provided)  of any  unpaid  interest,  the
      Holder shall immediately  deliver the Debenture,  appropriately  marked to
      indicate payment in full thereof,  to the Issuer or its assignee  pursuant
      to Issuer or its assignee's instructions.

5.    No provision of this Debenture shall alter or impair the obligation of the
      Issuer, which is absolute and unconditional,  to pay the principal of, and
      interest on, this Debenture at the place,  time and rate, and in the coins
      or currency, herein prescribed.

6.    The Issuer hereby  expressly  waives demand and  presentment  for payment,
      notice of  nonpayment,  protest,  notice of protest,  notice of  dishonor,
      notice  of  acceleration  or intent to  accelerate,  bringing  of suit and
      diligence  in taking any action to collect  amounts  called for  hereunder
      and shall be  directly  and  primarily  liable for the payment of all sums
      owing  and to be owing  hereon,  regardless  of and  without  any  notice,
      diligence,  act or omission as or with  respect to the  collection  of any
      amount called for hereunder.

7.    The  Issuer  agrees  to pay all cost and  expenses,  including  reasonable
      attorneys'  fees,  which may be incurred by the Holder in  collecting  any
      amount due or exercising the conversion rights under this Debenture.

8.    If one or  more of the  following  described  "Events  of  Default"  shall
      occur:

      (a)   The Issuer  shall  default in the payment of  principal  or interest
            on this Debenture; or

      (b)   Any of the  representations or warranties made by the Issuer herein,
            in the Subscription Agreement, or in any certificate or financial or
            other statements  heretofore or hereafter  furnished by or on behalf
            of the Issuer in connection  with the execution and delivery of this
            Debenture or the Subscription Agreement shall be false or misleading
            in any material respect at the time; or

      (c)   The Issuer shall fail to issue the  Conversion  Shares in accordance
            with  the  terms  of  conversion  set out in  Section  4 above or to
            perform or observe any other covenant,  term, provision,  condition,
            agreement or obligation of the Issuer under this  Debenture and such
            failure shall continue  uncured for a period of seven (7) days after
            notice from the Holder of such failure; or

      (d)   The Issuer  shall (1)  become  insolvent;  (2) admit in writing  its
            inability  to pay its debt  generally  as they  mature;  (3) make an
            assignment for the benefit of creditors or commence  proceedings for
            its dissolution; or (4) apply for or consent to the appointment of a
            trustee,  liquidator or receiver for it or for a substantial part of
            its property or business; or

      (e)   A trustee,  liquidator or receiver shall be appointed for the Issuer
            or a  substantial  part of its  property  or  business  without  its
            consent and shall not be  discharged  within  thirty (30) days after
            such appointment; or

      (f)   Any  governmental  agency or any court of competent  jurisdiction at
            the instance of any  governmental  agency  shall  assume  custody or
            control off the whole or any  substantial  portion of the properties
            or assets of the Issuer  and shall not be  dismissed  within  thirty
            (30) calendar days thereafter; or

      (g)   Bankruptcy,  reorganization,  insolvency or liquidation  proceedings
            or other  proceedings  for relief  under any  bankruptcy  law or any
            law for the  relief of  debtors  shall be  instituted  by or against
            the Issuer,  and if  instituted  against  the  Issuer,  shall not be
            dismissed  within thirty (30)  calendar days after such  institution
            or the Issuer  shall by any  action or answer  approve  of,  consent
            to, or  acquiesce  in any such  proceedings  or audit  the  material
            allegations  of, or default in  answering  a petition  filed in such
            proceeding; or

      (h)   The Issuer's Common Stock shall cease to be quoted on any of the New
            York  Stock  Exchange,  American  Stock  Exchange,   NASDAQ-National
            Market,  NASDAQ-Small  Cap or OTC  Electronic  Bulletin  Board for a
            period in excess of ninety (90) Calendar Days.

      Then, or at any time thereafter,  and in each and every such case,  unless
      such  Event of  Default  shall  have been  waived in writing by the Holder
      (which  waiver  shall  not be  deemed  to be a  waiver  of any  subsequent
      default) at the option of the Holder and in the Holder's sole  discretion,
      the  Holder may  consider  this  Debenture  immediately  due and  payable,
      without presentment,  demand,  protest or notice of any kind, all of which
      are  hereby  expressly  waived,  anything  herein  or in any note or other
      instruments contained to the contrary notwithstanding,  and the Holder may
      immediately,  and without  expiration of any period of grace,  enforce any
      and all of the Holder's  rights and remedies  provided herein or nay other
      rights or remedies afforded by law.

9.    No  recourse  shall be had for the  payment  of the  principal  of, or the
      interest on, this Debenture,  or for any claim based hereon,  or otherwise
      in respect  hereof,  against  any  incorporator,  shareholder,  officer or
      director,  as  such,  past,  present  or  future,  of  the  Issuer  or any
      successor  corporation,  whether by virtue of any constitution,  statue or
      rule  of  law,  or  by   enforcement  by  any  assessment  or  penalty  or
      otherwise,  all such liability being, by acceptance  hereof and as part of
      the consideration for the issue hereof expressly waived and released.

10.   The Holder of this Debenture,  by execution of the Subscription  Agreement
      and  acceptance  hereof agrees that this  Debenture is being  acquired for
      investment purposes and that such Holder will not offer, sell or otherwise
      dispose of this  debenture  or the shares of Common  Stock  issuable  upon
      conversion thereof except under  circumstances which shall not result in a
      violation of the Act or any applicable  State Blue Sky law or similar laws
      relating to the sale of securities.

11.   By  acceptance of this  Debenture,  the Holder hereby grants to the Issuer
      or its assignee the option ("Prepayment  Option"),  for a period beginning
      after  February 15, 1998 to repurchase all of the  outstanding  portion of
      the  Debenture  plus  accrued  interest,  after  sixty (60) days notice to
      Holder  during  which  sixty (60) days  Holder may  convert in  accordance
      with Holder's  conversion  privileges  hereunder.  The repurchase price of
      this  Debenture  (the  "Repurchase  Price")  shall be equal to One Hundred
      Five  Percent  (105%)  of  the  full  unpaid   principal   amount  of  the
      Debenture,   plus  accrued  interest  payable  in  cash.  This  Prepayment
      Option may be exercised by written  notice via  telecopy  transmission  to
      the Holder (with  written  notice to the  registered  address by overnight
      courier) after  February 15, 1998 and delivery of the Repurchase  Price to
      the  Holder on or before  the fifth  (5th)  NASDAQ  trading  day after the
      last day of such  sixty  (60) day  notice  period or the date on which the
      Holder  notifies  the Issuer that the Holder  elects not to  exercise  the
      Holder's  conversion  privileges  hereunder,  whichever  is  sooner.  Upon
      receipt of the  Repurchase  Price,  Holder shall  immediately  deliver the
      Debenture,  appropriately  marked to indicate payment in full thereof,  to
      the  Issuer  or its  assignee  pursuant  to  Issuer's  or  its  assignee's
      instructions.

12.   In  the  case  that  there  is any  outstanding  amount  of the  Debenture
      unconverted on March 11, 2000, the outstanding  unconverted portion of the
      Debenture  will  be  subject  to  automatic  conversion  pursuant  to  the
      provisions of the last four sentences in Section 4 hereunder.

13.   In case any  provision  of this  Debenture is held by a court of competent
      jurisdiction   to  be  excessive   in  scope  or   otherwise   invalid  or
      unenforceable  such  provision  shall be adjusted  rather than voided,  if
      possible, so that such is enforceable to the maximum extent possible,  and
      the  validity  and  enforceability  of the  remaining  provisions  of this
      debenture will not in any way be affected or impaired thereby.

14.   This Debenture and the agreements referred to in this Debenture constitute
      the full and entire understanding and agreement between the Issuer and the
      Holder with respect  hereof.  Neither this  Debenture nor any terms hereof
      may be amended,  waived,  discharged or terminated other than by a written
      statement signed by the Issuer and the Holder.

15.   This Debenture  shall be governed by and construed in accordance  with the
      laws of the  state  of  Delaware  and the  United  State of  America.  Any
      judicial proceedings relating to the interpretation and performance of the
      terms and  conditions of this  Debenture  shall be conducted in such state
      and Federal  courts  located in the City,  County and State of New York as
      may be appropriate in each instance.


IN WITNESS  WHEREOF the Issuer has caused this instrument to be duly executed by
an officer thereunto duly authorized.

ISSUER:
NOISE CANCELLATION
TECHNOLOGIES, INC.



By:   /s/ STEPHEN J. FOGARTY
      Official Signatory of Issuer


Name (Printed:)   Stephen J. Fogarty

Title:            Senior Vice-President and Chief Financial Officer

Date              March 11, 1997



<PAGE>


                                    EXHIBIT 1
                              Notice of Conversion
  (To be executed by the Registered Holder in order to Convert the Debenture)

             TO:  Noise Cancellation Technologies, Inc.
                  One Dock Street
                  Stamford, Connecticut  06902
                  Attention:  John Horton, General Counsel
                  Fax:  (203) 348-4106
                  Tel:  (203) 961-0500 ext. 388

The  undersigned  (the  "Holder")  hereby  irrevocably  elects to convert  Fifty
Thousand  (USD  $50,000.00)  of  the  Debenture  No.___  of  NOISE  CANCELLATION
TECHNOLOGIES,  INC. (the "Issuer") according to the conditions set forth in such
Debenture,  as of the date  written  below.  The  shares are to be issued in the
"Street Name" written below:

The undersigned represents and warrants as follows:

(a)   The offer to convert the Debenture  was made to the Issuer  outside of the
      United States and the undersigned was, at the time the  subscription  form
      was executed and delivered, and is now outside the United States;

(b)   It is not a U.S.  person (as such term is  defined  in  Section  902(a) of
      Regulation  S  ("Regulation  S")  promulgated   under  the  United  States
      Securities Act of 1933 (the  "Securities  Act");  and it is converting the
      Debenture  for its own  account  and not for the account or benefit of any
      U.S. person;

(c)   All offers  and sales of the Common  Stock  shall be made  pursuant  to an
      effective  registration  statement under the Securities Act or pursuant to
      an exemption  from, or in a transaction  not subject to, the  registration
      requirements of the Securities Act;

(d)   It is  familiar  with  and  understands  the  terms  and  conditions,  and
      requirements  contained in Regulation S and  definitions  of U.S.  persons
      contained in Regulation S.


Holder:     AUSTOST ANSTALT SCHAAN(seal)

By:         ____________________________
            Official Signatory of Holder

Title:      ______________________  Country of Execution:  Liechtenstein


<PAGE>


Conversion Date (See Section 4)                 ________________
Closing Bid on the Closing Date (See Section 4) ________________
Average Closing Bid Price (See Section 4)       ________________
Conversion Price (See Section 4)                ________________
Number of common shares to be
received by Holder (see Section 4)              ________________

Name of Holder for Registration                 ________________

Address for Registration                        ________________

                                                ________________

"Street Name" for certificate                   ________________






<PAGE>


EXHIBIT 4(c)

No. __                                                        USD$50,000.00

                      NOISE CANCELLATION TECHNOLOGIES, INC.

                  8% CONVERTIBLE DEBENTURE DUE March 12, 2000

THE DEBENTURE  REPRESENTED BY THIS CERTIFICATE AND THE SECURITIES  ISSUABLE UPON
CONVERSION  HEREOF HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED.  THE  DEBENTURE  HAS BEEN  ACQUIRED  FOR  INVESTMENT  AND NEITHER  THIS
DEBENTURE  NOR THE  SECURITIES  ISSUABLE  UPON  CONVERSION  HEREOF  MAY BE SOLD,
TRANSFERRED  OR ASSIGNED IN THE ABSENCE OF AN EFFECTIVE  REGISTRATION  STATEMENT
FOR THE DEBENTURE OR SUCH  SECURITIES,  AS THE CASE MAY BE, UNDER THE SECURITIES
ACT OF 1933, AS AMENDED,  OR AN OPINION OF COUNSEL IN FORM,  SUBSTANCE AND SCOPE
REASONABLY ACCEPTABLE TO THE ISSUER THAT REGISTRATION IS NOT REQUIRED UNDER SAID
ACT OR  UNLESS  SOLD  PURSUANT  TO RULE 144  UNDER  SAID  ACT.  ANY  SUCH  SALE,
ASSIGNMENT OR TRANSFER MUST ALSO COMPLY WITH APPLICABLE STATE SECURITIES LAW.

THIS  DEBENTURE  is  one of a duly  authorized  issue  of  Debentures  of  NOISE
CANCELLATION TECHNOLOGIES, INC., a corporation duly organized and existing under
the laws of the State of Delaware (the "Issuer") designated as its Eight Percent
(8%) Non-Voting  Subordinated  Convertible  Debentures due MARCH 12, 2000, in an
aggregate  principle  amount  of One  Hundred  Thousand  United  States  Dollars
(USD$100,000.00).

FOR VALUE RECEIVED, the Issuer promises to pay to

                   Optimum Fund
                   P.O. Box 2003
                   Georgetown, Grand Cayman
                   Grand Cayman Islands
                   British Virgin Islands

the  registered  holder hereof and its  successors  and assigns (the  "Holder"),
the principle sum of

                                 FIFTY THOUSAND
                      UNITED STATES DOLLARS (USD$50,000.00)

                                       on
                                 March 12, 2000
                             (the "Maturity Date"),



<PAGE>



and to pay  interest  on the  principle  sum  outstanding  at the  rate of Eight
Percent (8%) per annum due and payable on March 31st, June 30th,  September 30th
and December 31st of each year until maturity. Interest shall begin to accrue on
the closing date applicable to the issuance of this Debenture as provided in the
"Subscription  Agreement"  defined below (the "Closing  Date").  Payment of each
interest payment may, at the Issuer's option,  be made in cash or by delivery of
the shares of the Issuer's Common Stock ("Common  Stock").  The number of shares
to be  delivered  shall be based on one  hundred  percent  (100%) of the average
closing  bid price of the  Issuer's  Common  Stock as reported on NASDAQ for the
Five (5) Trading  Days  immediately  preceding  the record date for the interest
payment.  The  interest so payable will be paid to the person in whose name this
Debenture is registered on the record of the Issuer  regarding  registration and
transfers of the Debenture (the "Debenture Register");  provided,  however, that
the Issuer's  obligation to a transferee of this  Debenture  arises only if such
transfer,  sale or other  disposition  is made in accordance  with the terms and
conditions of the Offshore Debenture Securities  Subscription Agreement dated as
of  March  12,  1997  between  the  Issuer  and the  Holder  (the  "Subscription
Agreement"). The principle of, and interest of this Debenture (to the extent not
payable by delivery of shares of Issuer's  Common Stock in  accordance  with the
terms  thereof)  are payable in such coin or  currency  of the United  States of
America  as at the time of payment  is legal  tender  for  payment of public and
private debts,  at the address last  appearing on the debenture  Register of the
Issuer as  designated  in writing by the Holder  hereof  from time to time.  The
Issuer will pay the  principal of and accrued and unpaid  interest due upon this
debenture on the Maturity Date, less any amounts  required by law to be deducted
or withheld,  to the Holder at the last address on the Debenture  Register.  The
receipt of such check or shares of Common  Stock shall  constitute  a payment of
principal  and interest  hereunder and shall satisfy and discharge the liability
for  principal  and  interest  on  this  Debenture  to the  extent  of  the  sum
represented  by such  check or  shares  of  Common  Stock  plus any  amounts  so
deducted.

This Debenture is subject to the following additional provisions:

1.    The Debentures  are issuable in  denominations  of Fifty  Thousand  United
      States Dollars (USD$50,000.00).

2.    The Issuer  shall be entitled to withhold  from all  payments of principle
      of, and interest on, this Debenture any amounts required to withheld under
      the  applicable  provisions  of the  United  States  income  tax or  other
      applicable laws at the time of such payments.

3.    This   Debenture  has  been  issued   subject  to  investment   and  other
      representations  of  the  original  Holder  hereof  as  set  forth  in the
      Subscription  Agreement and may be  transferred or exchanged in the United
      States only in  compliance  with the  Securities  Act of 1933,  as amended
      (the  "Act")  and  applicable  state  securities  laws.  Prior  to the due
      presentment  for such  transfer  of this  Debenture,  the  Issuer  and any
      agent of the Issuer may treat the person in whose name this  Debenture  is
      duly  registered  on the Issuer's  Debenture  Register as the owner hereof
      for the purpose of receiving  payment as provided and all other  purposes,
      whether or not this  Debenture be overdue,  and neither the Issuer nor any
      agent shall be affected by notice to contrary.

 4.    The  Holder  of  this  Debenture  is  entitled,  at  its  option,  at any
      time  commencing  on or after  forty-five  (45)  days  after  the  Closing
      Date to convert the full unpaid  principle  amount of this  Debenture into
      shares  of Common  Stock of the  Issuer  (the  "Conversion  Shares")  at a
      conversion  price  (the  "Conversion  Price")  for each  Conversion  Share
      equal to the lesser of  eighty-five  percent  (85%) of the  closing bid of
      the  Common  Stock on the  Closing  Date or seventy  percent  (70%) of the
      average  closing  bid price of the  Common  Stock for the five (5)  NASDAQ
      Trading Days  immediately  preceding the Conversion  Date (as  hereinafter
      defined),  as reported by the National  Association of Securities  Dealers
      Automated  Quotation  System.  Provided,  however,  that in no event shall
      the  Conversion  Price ever be less than  $0.23 per  share.  The number of
      Conversion  Shares to be  received  by Holder on  conversion  shall be the
      product of the unpaid  principal  amount of the Debenture  being converted
      divided by the  Conversion  Price.  On the Closing  Date as defined in the
      Subscription  Agreement,  the Issuer will reserve on its books one hundred
      eighty-seven  thousand five hundred  (187,500)  shares of Common Stock for
      use in  connection  with  conversion  of this  Debenture.  The Issuer does
      hereby  irrevocably  agree to  instruct  its  Transfer  Agent  to  provide
      Common Stock  Certificates  representing  Conversion  Shares to the Holder
      in accordance  with the terms of conversion  hereinafter  set out.  Holder
      shall not sell any Conversion  Shares so converted  until  forty-five (45)
      days after the  Closing  Date.  Such  conversion  by the  Holder  shall be
      effected  by the Holder  surrendering  to the Issuer this  Debenture  with
      the form of Conversion  Notice  attached  hereto as Exhibit 1, executed by
      the Holder of this Debenture and  accompanied,  if required by the Issuer,
      by proper  assignment  hereof in blank  delivered  in the  manner and time
      period  as  hereinafter  set out.  The  Issuer  shall  then  instruct  its
      Transfer  Agent to deliver the  appropriate  Common Stock  Certificate  to
      the  Holder.  For  purposes  of  this  Debenture,  the  "Conversion  Date"
      shall be deemed to be the date on which the Holder  has sent by  facsimile
      the executed  and  completed  Conversion  notice  together  with a copy of
      this Debenture and any applicable  executed  assignment to the Issuer.  In
      order to convert,  this  Debenture  together with the Original  Conversion
      Notice duly executed,  must be delivered by express  courier to the Issuer
      within  Two  (2)  NASDAQ  Trading  Days  of  the   Conversion   Date.  The
      Conversion  Shares must be issued and  returned by the  Transfer  Agent to
      the Holder by express  courier  with Five (5)  NASDAQ  Trading  Days after
      the Conversion  Date.  Accrued but unpaid  interest  shall,  at the option
      of the Issuer,  be subject to  conversion  under the terms and  conditions
      concerning  the  payment  of  interest  set  forth  above  at the  time of
      conversion  of  this  Debenture  or at the  time  any  quarterly  interest
      payments are due. No fractional  shares or scrip  representing  fractional
      shares  will be issued on  conversion,  but the number of shares  issuable
      shall be rounded to the nearest  whole  share.  The Issuer may, at its own
      option,  cause the  automatic  conversion  into  Conversion  Shares of the
      full  unpaid  amount of this  Debenture  after  February  15,  1998 at the
      aforesaid  Conversion  Price.  The Issuer may exercise its option to cause
      the  automatic  conversion  as set forth herein after said sixty (60) days
      notice to Holder  during  which  sixty  (60) days  Holder  may  convert in
      accordance  with  Holder's  conversion  privileges  hereunder.  After  the
      sixty (60) days and the  exercise  of said  automatic  conversion,  Issuer
      may only exercise further  automatic  conversion(s) in connection with not
      less than  twenty-five  percent  (25%) of the then  remaining  amounts  of
      outstanding  Conversion  Shares  pertaining  to  all  of  the  unconverted
      Debentures  per  automatic  conversion  and only  after  thirty  (30) days
      notice to Holder  during  which  thirty  (30) days  Holder may  convert in
      accordance  with  Holder's  conversion  privileges  hereunder.  The option
      shall be effectively  exercised on the date on which the Issuer  transmits
      by  facsimile  transmission  and mails  notice of said  conversion  to the
      registered  Holder of the effected  Debentures.  To effect such conversion
      by the Issuer,  the Conversion  Shares must be issued and delivered by the
      Transfer  Agent to the  Holder by  express  courier on or before the fifth
      (5th)  NASDAQ  Trading Day after the last day of such sixty (60) or thirty
      (30) day  notice  period,  as the case  may be,  or the date on which  the
      Holder  notifies  the Issuer that the Holder  elects not to  exercise  the
      Holder's   conversion   privileges   hereunder.   Upon   receipt   of  the
      Conversion  Shares  and the  payment  (in cash or  Common  Stock as herein
      provided) of any unpaid  interest,  the Holder shall  immediately  deliver
      the Debenture,  appropriately  marked to indicate payment in full thereof,
      to the  Issuer  or its  assignee  pursuant  to  Issuer  or its  assignee's
      instructions.

5.    No provision of this Debenture shall alter or impair the obligation of the
      Issuer, which is absolute and unconditional,  to pay the principal of, and
      interest on, this Debenture at the place,  time and rate, and in the coins
      or currency, herein prescribed.

6.    The Issuer hereby  expressly  waives demand and  presentment  for payment,
      notice of  nonpayment,  protest,  notice of protest,  notice of  dishonor,
      notice  of  acceleration  or intent to  accelerate,  bringing  of suit and
      diligence  in taking any action to collect  amounts  called for  hereunder
      and shall be  directly  and  primarily  liable for the payment of all sums
      owing  and to be owing  hereon,  regardless  of and  without  any  notice,
      diligence,  act or omission as or with  respect to the  collection  of any
      amount called for hereunder.

7.    The  Issuer  agrees  to pay all cost and  expenses,  including  reasonable
      attorneys'  fees,  which may be incurred by the Holder in  collecting  any
      amount due or exercising the conversion rights under this Debenture.

8.    If one or  more of the  following  described  "Events  of  Default"  shall
      occur:

      (a)   The Issuer  shall  default in the payment of  principal  or interest
            on this Debenture; or

      (b)   Any of the  representations or warranties made by the Issuer herein,
            in the Subscription Agreement, or in any certificate or financial or
            other statements  heretofore or hereafter  furnished by or on behalf
            of the Issuer in connection  with the execution and delivery of this
            Debenture or the Subscription Agreement shall be false or misleading
            in any material respect at the time; or

      (c)   The Issuer shall fail to issue the  Conversion  Shares in accordance
            with  the  terms  of  conversion  set out in  Section  4 above or to
            perform or observe any other covenant,  term, provision,  condition,
            agreement or obligation of the Issuer under this  Debenture and such
            failure shall continue  uncured for a period of seven (7) days after
            notice from the Holder of such failure; or

      (d)   The Issuer  shall (1)  become  insolvent;  (2) admit in writing  its
            inability  to pay its debt  generally  as they  mature;  (3) make an
            assignment for the benefit of creditors or commence  proceedings for
            its dissolution; or (4) apply for or consent to the appointment of a
            trustee,  liquidator or receiver for it or for a substantial part of
            its property or business; or

      (e)   A trustee,  liquidator or receiver shall be appointed for the Issuer
            or a  substantial  part of its  property  or  business  without  its
            consent and shall not be  discharged  within  thirty (30) days after
            such appointment; or

      (f)   Any  governmental  agency or any court of competent  jurisdiction at
            the instance of any  governmental  agency  shall  assume  custody or
            control off the whole or any  substantial  portion of the properties
            or assets of the Issuer  and shall not be  dismissed  within  thirty
            (30) calendar days thereafter; or

      (g)   Bankruptcy,  reorganization,  insolvency or liquidation  proceedings
            or other  proceedings  for relief  under any  bankruptcy  law or any
            law for the  relief of  debtors  shall be  instituted  by or against
            the Issuer,  and if  instituted  against  the  Issuer,  shall not be
            dismissed  within thirty (30)  calendar days after such  institution
            or the Issuer  shall by any  action or answer  approve  of,  consent
            to, or  acquiesce  in any such  proceedings  or audit  the  material
            allegations  of, or default in  answering  a petition  filed in such
            proceeding; or

      (h)   The Issuer's Common Stock shall cease to be quoted on any of the New
            York  Stock  Exchange,  American  Stock  Exchange,   NASDAQ-National
            Market,  NASDAQ-Small  Cap or OTC  Electronic  Bulletin  Board for a
            period in excess of ninety (90) Calendar Days.

      Then, or at any time thereafter,  and in each and every such case,  unless
      such  Event of  Default  shall  have been  waived in writing by the Holder
      (which  waiver  shall  not be  deemed  to be a  waiver  of any  subsequent
      default) at the option of the Holder and in the Holder's sole  discretion,
      the  Holder may  consider  this  Debenture  immediately  due and  payable,
      without presentment,  demand,  protest or notice of any kind, all of which
      are  hereby  expressly  waived,  anything  herein  or in any note or other
      instruments contained to the contrary notwithstanding,  and the Holder may
      immediately,  and without  expiration of any period of grace,  enforce any
      and all of the Holder's  rights and remedies  provided herein or nay other
      rights or remedies afforded by law.

9.    No  recourse  shall be had for the  payment  of the  principal  of, or the
      interest on, this Debenture,  or for any claim based hereon,  or otherwise
      in respect  hereof,  against  any  incorporator,  shareholder,  officer or
      director,  as  such,  past,  present  or  future,  of  the  Issuer  or any
      successor  corporation,  whether by virtue of any constitution,  statue or
      rule  of  law,  or  by   enforcement  by  any  assessment  or  penalty  or
      otherwise,  all such liability being, by acceptance  hereof and as part of
      the consideration for the issue hereof expressly waived and  released.

10.   The Holder of this Debenture,  by execution of the Subscription  Agreement
      and  acceptance  hereof agrees that this  Debenture is being  acquired for
      investment purposes and that such Holder will not offer, sell or otherwise
      dispose of this  debenture  or the shares of Common  Stock  issuable  upon
      conversion thereof except under  circumstances which shall not result in a
      violation of the Act or any applicable  State Blue Sky law or similar laws
      relating to the sale of securities.

11.   By  acceptance of this  Debenture,  the Holder hereby grants to the Issuer
      or its assignee the option ("Prepayment  Option"),  for a period beginning
      after  February 15, 1998 to repurchase all of the  outstanding  portion of
      the  Debenture  plus  accrued  interest,  after  sixty (60) days notice to
      Holder  during  which  sixty (60) days  Holder may  convert in  accordance
      with Holder's  conversion  privileges  hereunder.  The repurchase price of
      this  Debenture  (the  "Repurchase  Price")  shall be equal to One Hundred
      and  Five  Percent  (105%)  of the full  unpaid  principal  amount  of the
      Debenture,   plus  accrued  interest  payable  in  cash.  This  Prepayment
      Option may be exercised by written  notice via  telecopy  transmission  to
      the Holder (with  written  notice to the  registered  address by overnight
      courier)  after  February 15, 1998 and delivery of the  Repurchase  Monies
      to the Holder on or before the fifth  (5th)  NASDAQ  trading day after the
      last day of such  sixty  (60) day  notice  period or the date on which the
      Holder  notifies  the Issuer that the Holder  elects not to  exercise  the
      Holder's   conversion   privileges   hereunder.   Upon   receipt   of  the
      Repurchase  Monies,   Holder  shall  immediately  deliver  the  Debenture,
      appropriately  marked to indicate  payment in full thereof,  to the Issuer
      or its assignee pursuant to Issuer's or its assignee's instructions.

12.   In  the  case  that  there  is any  outstanding  amount  of the  Debenture
      unconverted on March 12, 2000, the outstanding  unconverted portion of the
      Debenture  will  be  subject  to  automatic  conversion  pursuant  to  the
      provisions of the last four sentences in Section 4 hereunder.

13.   In case any  provision  of this  Debenture is held by a court of competent
      jurisdiction   to  be  excessive   in  scope  or   otherwise   invalid  or
      unenforceable  such  provision  shall be adjusted  rather than voided,  if
      possible, so that such is enforceable to the maximum extent possible,  and
      the  validity  and  enforceability  of the  remaining  provisions  of this
      debenture will not in any way be affected or impaired thereby.

14.   This Debenture and the agreements referred to in this Debenture constitute
      the full and entire understanding and agreement between the Issuer and the
      Holder with respect  hereof.  Neither this  Debenture nor any terms hereof
      may be amended,  waived,  discharged or terminated other than by a written
      statement signed by the Issuer and the Holder.

15.   This Debenture  shall be governed by and construed in accordance  with the
      laws of the state of Delaware and the United State of America.




<PAGE>


IN WITNESS  WHEREOF the Issuer has caused this instrument to be duly executed by
an officer thereunto duly authorized.

ISSUER:
NOISE CANCELLATION
TECHNOLOGIES, INC.



By:  /s/ STEPHEN J. FOGARTY
     Official Signatory of Issuer


Name (Printed:) Stephen J. Fogarty

Title:          Senior Vice-President and Chief Financial Officer

Date:           March 12, 1997


<PAGE>


                                    EXHIBIT 1
                              Notice of Conversion
  (To be executed by the Registered Holder in order to Convert the Debenture)

             TO:  Noise Cancellation Technologies, Inc.
                  One Dock Street
                  Stamford, Connecticut  06902
                  Attention:  John Horton, General Counsel
                  Fax:  (203) 348-4106
                  Tel:  (203) 961-0500 ext. 388

The  undersigned  (the  "Holder")  hereby  irrevocably  elects to convert  Fifty
Thousand  (USD  $50,000.00)  of  the  Debenture  No.__  of  NOISE   CANCELLATION
TECHNOLOGIES,  INC. (the "Issuer") according to the conditions set forth in such
Debenture,  as of the date  written  below.  The  shares are to be issued in the
"Street Name" written below:

The undersigned represents and warrants as follows:

(a)   The offer to convert the Debenture  was made to the Issuer  outside of the
      United States and the undersigned was, at the time the  subscription  form
      was executed and delivered, and is now outside the United States;

(b)   It is not a U.S.  person (as such term is  defined  in  Section  902(a) of
      Regulation  S  ("Regulation  S")  promulgated   under  the  United  States
      Securities Act of 1933 (the  "Securities  Act");  and it is converting the
      Debenture  for its own  account  and not for the account or benefit of any
      U.S. person;

(c)   All offers  and sales of the Common  Stock  shall be made  pursuant  to an
      effective  registration  statement under the Securities Act or pursuant to
      an exemption  from, or in a transaction  not subject to, the  registration
      requirements of the Securities Act;

(d)   It is  familiar  with  and  understands  the  terms  and  conditions,  and
      requirements  contained in Regulation S and  definitions  of U.S.  persons
      contained in Regulation S.

Holder:     OPTIMUM FUND (seal)

            By:__________________________
               Official Signatory of Holder

Title:______________________________ Country of Execution:____________


<PAGE>


Conversion Date (See Section 4)                 __________________
Closing Bid on the Closing Date (See Section 4) __________________
Average Closing Bid Price (See Section 4)       __________________
Conversion Price (See Section 4)                __________________
Number of common shares to be
received by Holder (see Section 4)              __________________


Name of Holder for Registration                 __________________

Address for Registration                        __________________

                                                __________________

"Street Name" for certificate                   __________________




<PAGE>


EXHIBIT 4(d)

No. __                                                        USD$50,000.00

                      NOISE CANCELLATION TECHNOLOGIES, INC.

                  8% CONVERTIBLE DEBENTURE DUE March 14, 2000

THE DEBENTURE  REPRESENTED BY THIS CERTIFICATE AND THE SECURITIES  ISSUABLE UPON
CONVERSION  HEREOF HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED.  THE  DEBENTURE  HAS BEEN  ACQUIRED  FOR  INVESTMENT  AND NEITHER  THIS
DEBENTURE  NOR THE  SECURITIES  ISSUABLE  UPON  CONVERSION  HEREOF  MAY BE SOLD,
TRANSFERRED  OR ASSIGNED IN THE ABSENCE OF AN EFFECTIVE  REGISTRATION  STATEMENT
FOR THE DEBENTURE OR SUCH  SECURITIES,  AS THE CASE MAY BE, UNDER THE SECURITIES
ACT OF 1933, AS AMENDED,  OR AN OPINION OF COUNSEL IN FORM,  SUBSTANCE AND SCOPE
REASONABLY ACCEPTABLE TO THE ISSUER THAT REGISTRATION IS NOT REQUIRED UNDER SAID
ACT OR  UNLESS  SOLD  PURSUANT  TO RULE 144  UNDER  SAID  ACT.  ANY  SUCH  SALE,
ASSIGNMENT OR TRANSFER MUST ALSO COMPLY WITH APPLICABLE STATE SECURITIES LAW.


THIS  DEBENTURE  is  one of a duly  authorized  issue  of  Debentures  of  NOISE
CANCELLATION TECHNOLOGIES, INC., a corporation duly organized and existing under
the laws of the State of Delaware (the "Issuer") designated as its Eight Percent
(8%) Non-Voting  Subordinated  Convertible  Debentures due MARCH 14, 2000, in an
aggregate  principle  amount of One Hundred Fifty Thousand United States Dollars
(USD$150,000.00).

FOR VALUE RECEIVED, the Issuer promises to pay to

                   Sage Capital Investments Limited
                   P.O. Box N-4826
                   Marron House, Virginia Street
                   Nassau, Bahamas

the  registered  holder hereof and its  successors  and assigns (the  "Holder"),
the principle sum of

                                 FIFTY THOUSAND
                      UNITED STATES DOLLARS (USD$50,000.00)

                                       on
                                 March 14, 2000
                             (the "Maturity Date"),



<PAGE>



and to pay  interest  on the  principle  sum  outstanding  at the  rate of Eight
Percent (8%) per annum due and payable on March 31st, June 30th,  September 30th
and December 31st of each year until maturity. Interest shall begin to accrue on
the closing date applicable to the issuance of this Debenture as provided in the
"Subscription  Agreement"  defined below (the "Closing  Date").  Payment of each
interest payment may, at the Issuer's option,  be made in cash or by delivery of
the shares of the Issuer's Common Stock ("Common  Stock").  The number of shares
to be  delivered  shall be based on one  hundred  percent  (100%) of the average
closing  bid price of the  Issuer's  Common  Stock as reported on NASDAQ for the
Five (5) Trading  Days  immediately  preceding  the record date for the interest
payment.  The  interest so payable will be paid to the person in whose name this
Debenture is registered on the record of the Issuer  regarding  registration and
transfers of the Debenture (the "Debenture Register");  provided,  however, that
the Issuer's  obligation to a transferee of this  Debenture  arises only if such
transfer,  sale or other  disposition  is made in accordance  with the terms and
conditions of the Offshore Debenture Securities  Subscription Agreement dated as
of  March  14,  1997  between  the  Issuer  and the  Holder  (the  "Subscription
Agreement"). The principle of, and interest of this Debenture (to the extent not
payable by delivery of shares of Issuer's  Common Stock in  accordance  with the
terms  thereof)  are payable in such coin or  currency  of the United  States of
America  as at the time of payment  is legal  tender  for  payment of public and
private debts,  at the address last  appearing on the debenture  Register of the
Issuer as  designated  in writing by the Holder  hereof  from time to time.  The
Issuer will pay the  principal of and accrued and unpaid  interest due upon this
debenture on the Maturity Date, less any amounts  required by law to be deducted
or withheld,  to the Holder at the last address on the Debenture  Register.  The
receipt of such check or shares of Common  Stock shall  constitute  a payment of
principal  and interest  hereunder and shall satisfy and discharge the liability
for  principal  and  interest  on  this  Debenture  to the  extent  of  the  sum
represented  by such  check or  shares  of  Common  Stock  plus any  amounts  so
deducted.

This Debenture is subject to the following additional provisions:

1.    The Debentures  are issuable in  denominations  of Fifty  Thousand  United
      States Dollars (USD$50,000.00).

2.    The Issuer  shall be entitled to withhold  from all  payments of principle
      of, and interest on, this Debenture any amounts required to withheld under
      the  applicable  provisions  of the  United  States  income  tax or  other
      applicable laws at the time of such payments.

3.    This   Debenture  has  been  issued   subject  to  investment   and  other
      representations  of  the  original  Holder  hereof  as  set  forth  in the
      Subscription  Agreement and may be  transferred or exchanged in the United
      States only in  compliance  with the  Securities  Act of 1933,  as amended
      (the  "Act")  and  applicable  state  securities  laws.  Prior  to the due
      presentment  for such  transfer  of this  Debenture,  the  Issuer  and any
      agent of the Issuer may treat the person in whose name this  Debenture  is
      duly  registered  on the Issuer's  Debenture  Register as the owner hereof
      for the purpose of receiving  payment as provided and all other  purposes,
      whether or not this  Debenture be overdue,  and neither the Issuer nor any
      agent shall be affected by notice to contrary.

 4.    The Holder of this  Debenture  is  entitled,  at its option,  at any time
      commencing  on or after  forty-five  (45) days after the  Closing  Date to
      convert the full unpaid  principle  amount of this  Debenture  into shares
      of Common  Stock of the Issuer (the  "Conversion  Shares") at a conversion
      price (the  "Conversion  Price")  for each  Conversion  Share equal to the
      lesser of  eighty-five  percent  (85%) of the  closing  bid of the  Common
      Stock  on the  Closing  Date  or  seventy  percent  (70%)  of the  average
      closing  bid price of the  Common  Stock for the five (5)  NASDAQ  Trading
      Days immediately  preceding the Conversion Date (as hereinafter  defined),
      as reported by the National  Association of Securities  Dealers  Automated
      Quotation  System.   Provided,   however,  that  in  no  event  shall  the
      Conversion  Price  ever be less  than  $0.23  per  share.  The  number  of
      Conversion  Shares to be  received  by Holder on  conversion  shall be the
      product of the unpaid  principal  amount of the Debenture  being converted
      divided by the  Conversion  Price.  On the Closing  Date as defined in the
      Subscription  Agreement,  the Issuer will reserve on its books one hundred
      eighty-seven  thousand five hundred  (187,500)  shares of Common Stock for
      use in  connection  with  conversion  of this  Debenture.  The Issuer does
      hereby  irrevocably  agree to  instruct  its  Transfer  Agent  to  provide
      Common Stock  Certificates  representing  Conversion  Shares to the Holder
      in accordance  with the terms of conversion  hereinafter  set out.  Holder
      shall not sell any Conversion  Shares so converted  until  forty-five (45)
      days after the  Closing  Date.  Such  conversion  by the  Holder  shall be
      effected  by the Holder  surrendering  to the Issuer this  Debenture  with
      the form of Conversion  Notice  attached  hereto as Exhibit 1, executed by
      the Holder of this Debenture and  accompanied,  if required by the Issuer,
      by proper  assignment  hereof in blank  delivered  in the  manner and time
      period  as  hereinafter  set out.  The  Issuer  shall  then  instruct  its
      Transfer  Agent to deliver the  appropriate  Common Stock  Certificate  to
      the  Holder.  For  purposes  of  this  Debenture,  the  "Conversion  Date"
      shall be deemed to be the date on which the Holder  has sent by  facsimile
      the executed  and  completed  Conversion  notice  together  with a copy of
      this Debenture and any applicable  executed  assignment to the Issuer.  In
      order to convert,  this  Debenture  together with the Original  Conversion
      Notice duly executed,  must be delivered by express  courier to the Issuer
      within  Two  (2)  NASDAQ  Trading  Days  of  the   Conversion   Date.  The
      Conversion  Shares must be issued and  returned by the  Transfer  Agent to
      the Holder by express  courier  with Five (5)  NASDAQ  Trading  Days after
      the Conversion  Date.  Accrued but unpaid  interest  shall,  at the option
      of the Issuer,  be subject to  conversion  under the terms and  conditions
      concerning  the  payment  of  interest  set  forth  above  at the  time of
      conversion  of  this  Debenture  or at the  time  any  quarterly  interest
      payments are due. No fractional  shares or scrip  representing  fractional
      shares  will be issued on  conversion,  but the number of shares  issuable
      shall be rounded to the nearest  whole  share.  The Issuer may, at its own
      option,  cause the  automatic  conversion  into  Conversion  Shares of the
      full  unpaid  amount of this  Debenture  after  February  15,  1998 at the
      aforesaid  Conversion  Price.  The Issuer may exercise its option to cause
      the  automatic  conversion  as set forth herein after said sixty (60) days
      notice to Holder  during  which  sixty  (60) days  Holder  may  convert in
      accordance  with  Holder's  conversion  privileges  hereunder.  After  the
      sixty (60) days and the  exercise  of said  automatic  conversion,  Issuer
      may only exercise further  automatic  conversion(s) in connection with not
      less than  twenty-five  percent  (25%) of the then  remaining  amounts  of
      outstanding  Conversion  Shares  pertaining  to  all  of  the  unconverted
      Debentures  per  automatic  conversion  and only  after  thirty  (30) days
      notice to Holder  during  which  thirty  (30) days  Holder may  convert in
      accordance  with  Holder's  conversion  privileges  hereunder.  The option
      shall be effectively  exercised on the date on which the Issuer  transmits
      by  facsimile  transmission  and mails  notice of said  conversion  to the
      registered  Holder of the effected  Debentures.  To effect such conversion
      by the Issuer,  the Conversion  Shares must be issued and delivered by the
      Transfer  Agent to the  Holder by  express  courier on or before the fifth
      (5th)  NASDAQ  Trading Day after the last day of such sixty (60) or thirty
      (30) day  notice  period,  as the case  may be,  or the date on which  the
      Holder  notifies  the Issuer that the Holder  elects not to  exercise  the
      Holder's   conversion   privileges   hereunder.   Upon   receipt   of  the
      Conversion  Shares  and the  payment  (in cash or  Common  Stock as herein
      provided) of any unpaid  interest,  the Holder shall  immediately  deliver
      the Debenture,  appropriately  marked to indicate payment in full thereof,
      to the  Issuer  or its  assignee  pursuant  to  Issuer  or its  assignee's
      instructions.

5.    No provision of this Debenture shall alter or impair the obligation of the
      Issuer, which is absolute and unconditional,  to pay the principal of, and
      interest on, this Debenture at the place,  time and rate, and in the coins
      or currency, herein prescribed.

6.    The Issuer hereby  expressly  waives demand and  presentment  for payment,
      notice of  nonpayment,  protest,  notice of protest,  notice of  dishonor,
      notice  of  acceleration  or intent to  accelerate,  bringing  of suit and
      diligence  in taking any action to collect  amounts  called for  hereunder
      and shall be  directly  and  primarily  liable for the payment of all sums
      owing  and to be owing  hereon,  regardless  of and  without  any  notice,
      diligence,  act or omission as or with  respect to the  collection  of any
      amount called for hereunder.

7.    The  Issuer  agrees  to pay all cost and  expenses,  including  reasonable
      attorneys'  fees,  which may be incurred by the Holder in  collecting  any
      amount due or exercising the conversion rights under this Debenture.

8.    If one or  more of the  following  described  "Events  of  Default"  shall
      occur:

      (a)   The Issuer  shall  default in the payment of  principal  or interest
            on this Debenture; or

      (b)   Any of the  representations or warranties made by the Issuer herein,
            in the Subscription Agreement, or in any certificate or financial or
            other statements  heretofore or hereafter  furnished by or on behalf
            of the Issuer in connection  with the execution and delivery of this
            Debenture or the Subscription Agreement shall be false or misleading
            in any material respect at the time; or

      (c)   The Issuer shall fail to issue the  Conversion  Shares in accordance
            with  the  terms  of  conversion  set out in  Section  4 above or to
            perform or observe any other covenant,  term, provision,  condition,
            agreement or obligation of the Issuer under this  Debenture and such
            failure shall continue  uncured for a period of seven (7) days after
            notice from the Holder of such failure; or

      (d)   The Issuer  shall (1)  become  insolvent;  (2) admit in writing  its
            inability  to pay its debt  generally  as they  mature;  (3) make an
            assignment for the benefit of creditors or commence  proceedings for
            its dissolution; or (4) apply for or consent to the appointment of a
            trustee,  liquidator or receiver for it or for a substantial part of
            its property or business; or

      (e)   A trustee,  liquidator or receiver shall be appointed for the Issuer
            or a  substantial  part of its  property  or  business  without  its
            consent and shall not be  discharged  within  thirty (30) days after
            such appointment; or

      (f)   Any  governmental  agency or any court of competent  jurisdiction at
            the instance of any  governmental  agency  shall  assume  custody or
            control off the whole or any  substantial  portion of the properties
            or assets of the Issuer  and shall not be  dismissed  within  thirty
            (30) calendar days thereafter; or

      (g)   Bankruptcy,  reorganization,  insolvency or liquidation  proceedings
            or other  proceedings  for relief  under any  bankruptcy  law or any
            law for the  relief of  debtors  shall be  instituted  by or against
            the Issuer,  and if  instituted  against  the  Issuer,  shall not be
            dismissed  within thirty (30)  calendar days after such  institution
            or the Issuer  shall by any  action or answer  approve  of,  consent
            to, or  acquiesce  in any such  proceedings  or audit  the  material
            allegations  of, or default in  answering  a petition  filed in such
            proceeding; or

      (h)   The Issuer's Common Stock shall cease to be quoted on any of the New
            York  Stock  Exchange,  American  Stock  Exchange,   NASDAQ-National
            Market,  NASDAQ-Small  Cap or OTC  Electronic  Bulletin  Board for a
            period in excess of ninety (90) Calendar Days.

      Then, or at any time thereafter,  and in each and every such case,  unless
      such  Event of  Default  shall  have been  waived in writing by the Holder
      (which  waiver  shall  not be  deemed  to be a  waiver  of any  subsequent
      default) at the option of the Holder and in the Holder's sole  discretion,
      the  Holder may  consider  this  Debenture  immediately  due and  payable,
      without presentment,  demand,  protest or notice of any kind, all of which
      are  hereby  expressly  waived,  anything  herein  or in any note or other
      instruments contained to the contrary notwithstanding,  and the Holder may
      immediately,  and without  expiration of any period of grace,  enforce any
      and all of the Holder's  rights and remedies  provided herein or nay other
      rights or remedies afforded by law.

9.    No  recourse  shall be had for the  payment  of the  principal  of, or the
      interest on, this Debenture,  or for any claim based hereon,  or otherwise
      in respect  hereof,  against  any  incorporator,  shareholder,  officer or
      director,  as  such,  past,  present  or  future,  of  the  Issuer  or any
      successor  corporation,  whether by virtue of any constitution,  statue or
      rule  of  law,  or  by   enforcement  by  any  assessment  or  penalty  or
      otherwise,  all such liability being, by acceptance  hereof and as part of
      the consideration for the issue hereof expressly waived and  released.

10.   The Holder of this Debenture,  by execution of the Subscription  Agreement
      and  acceptance  hereof agrees that this  Debenture is being  acquired for
      investment purposes and that such Holder will not offer, sell or otherwise
      dispose of this  debenture  or the shares of Common  Stock  issuable  upon
      conversion thereof except under  circumstances which shall not result in a
      violation of the Act or any applicable  State Blue Sky law or similar laws
      relating to the sale of securities.

11.   By  acceptance of this  Debenture,  the Holder hereby grants to the Issuer
      or its assignee the option ("Prepayment  Option"),  for a period beginning
      after  February 15, 1998 to repurchase all of the  outstanding  portion of
      the  Debenture  plus  accrued  interest,  after  sixty (60) days notice to
      Holder  during  which  sixty (60) days  Holder may  convert in  accordance
      with Holder's  conversion  privileges  hereunder.  The repurchase price of
      this  Debenture  (the  "Repurchase  Price")  shall be equal to One Hundred
      and  Five  Percent  (105%)  of the full  unpaid  principal  amount  of the
      Debenture,   plus  accrued  interest  payable  in  cash.  This  Prepayment
      Option may be exercised by written  notice via  telecopy  transmission  to
      the Holder (with  written  notice to the  registered  address by overnight
      courier)  after  February 15, 1998 and delivery of the  Repurchase  Monies
      to the Holder on or before the fifth  (5th)  NASDAQ  trading day after the
      last day of such  sixty  (60) day  notice  period or the date on which the
      Holder  notifies  the Issuer that the Holder  elects not to  exercise  the
      Holder's   conversion   privileges   hereunder.   Upon   receipt   of  the
      Repurchase  Monies,   Holder  shall  immediately  deliver  the  Debenture,
      appropriately  marked to indicate  payment in full thereof,  to the Issuer
      or its assignee pursuant to Issuer's or its assignee's instructions.

12.   In  the  case  that  there  is any  outstanding  amount  of the  Debenture
      unconverted on March 14, 2000, the outstanding  unconverted portion of the
      Debenture  will  be  subject  to  automatic  conversion  pursuant  to  the
      provisions of the last four sentences in Section 4 hereunder.

13.   In case any  provision  of this  Debenture is held by a court of competent
      jurisdiction   to  be  excessive   in  scope  or   otherwise   invalid  or
      unenforceable  such  provision  shall be adjusted  rather than voided,  if
      possible, so that such is enforceable to the maximum extent possible,  and
      the  validity  and  enforceability  of the  remaining  provisions  of this
      debenture will not in any way be affected or impaired thereby.

14.   This Debenture and the agreements referred to in this Debenture constitute
      the full and entire understanding and agreement between the Issuer and the
      Holder with respect  hereof.  Neither this  Debenture nor any terms hereof
      may be amended,  waived,  discharged or terminated other than by a written
      statement signed by the Issuer and the Holder.

15.   This Debenture  shall be governed by and construed in accordance  with the
      laws of the state of Delaware and the United State of America.




<PAGE>


IN WITNESS  WHEREOF the Issuer has caused this instrument to be duly executed by
an officer thereunto duly authorized.

ISSUER:
NOISE CANCELLATION
TECHNOLOGIES, INC.



By:  /s/ STEPHEN J. FOGARTY
     Official Signatory of Issuer


Name (Printed:) Stephen J. Fogarty

Title:          Senior Vice-President and Chief Financial Officer

Date:           March 14, 1997


<PAGE>


                                    EXHIBIT 1
                              Notice of Conversion
  (To be executed by the Registered Holder in order to Convert the Debenture)

             TO:  Noise Cancellation Technologies, Inc.
                  One Dock Street
                  Stamford, Connecticut  06902
                  Attention:  John Horton, General Counsel
                  Fax:  (203) 348-4106
                  Tel:  (203) 961-0500 ext. 388

The  undersigned  (the  "Holder")  hereby  irrevocably  elects to convert  Fifty
Thousand  (USD  $50,000.00)  of  the  Debenture  No.___  of  NOISE  CANCELLATION
TECHNOLOGIES,  INC. (the "Issuer") according to the conditions set forth in such
Debenture,  as of the date  written  below.  The  shares are to be issued in the
"Street Name" written below:

The undersigned represents and warrants as follows:

(a)   The offer to convert the Debenture  was made to the Issuer  outside of the
      United States and the undersigned was, at the time the  subscription  form
      was executed and delivered, and is now outside the United States;

(b)   It is not a U.S.  person (as such term is  defined  in  Section  902(a) of
      Regulation  S  ("Regulation  S")  promulgated   under  the  United  States
      Securities Act of 1933 (the  "Securities  Act");  and it is converting the
      Debenture  for its own  account  and not for the account or benefit of any
      U.S. person;

(c)   All offers  and sales of the Common  Stock  shall be made  pursuant  to an
      effective  registration  statement under the Securities Act or pursuant to
      an exemption  from, or in a transaction  not subject to, the  registration
      requirements of the Securities Act;

(d)   It is  familiar  with  and  understands  the  terms  and  conditions,  and
      requirements  contained in Regulation S and  definitions  of U.S.  persons
      contained in Regulation S.

Holder:     SAGE CAPITAL INVESTMENTS LIMITED (seal)

            By:____________________________________
               Official Signatory of Holder

Title:______________________________ Country of Execution:____________


<PAGE>


Conversion Date (See Section 4)                 ________________
Closing Bid on the Closing Date (See Section 4) ________________
Average Closing Bid Price (See Section 4)       ________________
Conversion Price (See Section 4)                ________________
Number of common shares to be
received by Holder (see Section 4)              ________________


Name of Holder for Registration                 ________________

Address for Registration                        ________________

                                                ________________

"Street Name" for certificate                   ________________




<PAGE>


EXHIBIT 4(e)

No.  __                                                       USD$50,000.00

                      NOISE CANCELLATION TECHNOLOGIES, INC.

                  8% CONVERTIBLE DEBENTURE DUE March 25, 2000

THE DEBENTURE  REPRESENTED BY THIS CERTIFICATE AND THE SECURITIES  ISSUABLE UPON
CONVERSION  HEREOF HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED.  THE  DEBENTURE  HAS BEEN  ACQUIRED  FOR  INVESTMENT  AND NEITHER  THIS
DEBENTURE  NOR THE  SECURITIES  ISSUABLE  UPON  CONVERSION  HEREOF  MAY BE SOLD,
TRANSFERRED  OR ASSIGNED IN THE ABSENCE OF AN EFFECTIVE  REGISTRATION  STATEMENT
FOR THE DEBENTURE OR SUCH  SECURITIES,  AS THE CASE MAY BE, UNDER THE SECURITIES
ACT OF 1933, AS AMENDED,  OR AN OPINION OF COUNSEL IN FORM,  SUBSTANCE AND SCOPE
REASONABLY ACCEPTABLE TO THE ISSUER THAT REGISTRATION IS NOT REQUIRED UNDER SAID
ACT OR  UNLESS  SOLD  PURSUANT  TO RULE 144  UNDER  SAID  ACT.  ANY  SUCH  SALE,
ASSIGNMENT OR TRANSFER MUST ALSO COMPLY WITH APPLICABLE STATE SECURITIES LAW.


THIS  DEBENTURE  is  one of a duly  authorized  issue  of  Debentures  of  NOISE
CANCELLATION TECHNOLOGIES, INC., a corporation duly organized and existing under
the laws of the State of Delaware (the "Issuer") designated as its Eight Percent
(8%) Non-Voting  Subordinated  Convertible  Debentures due MARCH 25, 2000, in an
aggregate  principle  amount of Five  Hundred  Thousand  United  States  Dollars
(USD$500,000.00).

FOR VALUE RECEIVED, the Issuer promises to pay to

                   Optimum Fund
                   P.O. Box 2003
                   Georgetown, Grand Cayman
                   Grand Cayman Islands
                   British Virgin Islands

the  registered  holder hereof and its  successors  and assigns (the  "Holder"),
the principle sum of

                                 FIFTY THOUSAND
                      UNITED STATES DOLLARS (USD$50,000.00)

                                       on
                                 March 25, 2000
                             (the "Maturity Date"),



<PAGE>


and to pay  interest  on the  principle  sum  outstanding  at the  rate of Eight
Percent (8%) per annum due and payable on March 31st, June 30th,  September 30th
and December 31st of each year until maturity. Interest shall begin to accrue on
the closing date applicable to the issuance of this Debenture as provided in the
"Subscription  Agreement"  defined below (the "Closing  Date").  Payment of each
interest payment may, at the Issuer's option,  be made in cash or by delivery of
the shares of the Issuer's Common Stock ("Common  Stock").  The number of shares
to be  delivered  shall be based on one  hundred  percent  (100%) of the average
closing  bid price of the  Issuer's  Common  Stock as reported on NASDAQ for the
Five (5) Trading  Days  immediately  preceding  the record date for the interest
payment.  The  interest so payable will be paid to the person in whose name this
Debenture is registered on the record of the Issuer  regarding  registration and
transfers of the Debenture (the "Debenture Register");  provided,  however, that
the Issuer's  obligation to a transferee of this  Debenture  arises only if such
transfer,  sale or other  disposition  is made in accordance  with the terms and
conditions of the Offshore Debenture Securities  Subscription Agreement dated as
of  March  25,  1997  between  the  Issuer  and the  Holder  (the  "Subscription
Agreement"). The principle of, and interest of this Debenture (to the extent not
payable by delivery of shares of Issuer's  Common Stock in  accordance  with the
terms  thereof)  are payable in such coin or  currency  of the United  States of
America  as at the time of payment  is legal  tender  for  payment of public and
private debts,  at the address last  appearing on the debenture  Register of the
Issuer as  designated  in writing by the Holder  hereof  from time to time.  The
Issuer will pay the  principal of and accrued and unpaid  interest due upon this
debenture on the Maturity Date, less any amounts  required by law to be deducted
or withheld,  to the Holder at the last address on the Debenture  Register.  The
receipt of such check or shares of Common  Stock shall  constitute  a payment of
principal  and interest  hereunder and shall satisfy and discharge the liability
for  principal  and  interest  on  this  Debenture  to the  extent  of  the  sum
represented  by such  check or  shares  of  Common  Stock  plus any  amounts  so
deducted.

This Debenture is subject to the following additional provisions:

1. The  Debentures  are  issuable  in  denominations  of Fifty  Thousand  United
   States Dollars (USD$50,000.00).

2. The Issuer shall be entitled to withhold  from all payments of principle  of,
   and interest on, this  Debenture any amounts  required to withheld  under the
   applicable  provisions of the United  States  income tax or other  applicable
   laws at the time of such payments.

3. This   Debenture   has  been   issued   subject  to   investment   and  other
   representations   of  the  original   Holder  hereof  as  set  forth  in  the
   Subscription  Agreement  and may be  transferred  or  exchanged in the United
   States only in compliance  with the  Securities  Act of 1933, as amended (the
   "Act") and applicable state securities laws. Prior to the due presentment for
   such transfer of this  Debenture,  the Issuer and any agent of the Issuer may
   treat the  person in whose  name this  Debenture  is duly  registered  on the
   Issuer's  Debenture Register as the owner hereof for the purpose of receiving
   payment as provided and all other purposes,  whether or not this Debenture be
   overdue,  and neither the Issuer nor any agent shall be affected by notice to
   contrary.

 4.The  Holder  of this  Debenture  is  entitled,  at its  option,  at any  time
   commencing on or after forty-five (45) days after the Closing Date to convert
   the full  unpaid  principle  amount of this  Debenture  into shares of Common
   Stock of the Issuer  (the  "Conversion  Shares") at a  conversion  price (the
   "Conversion  Price")  for  each  Conversion  Share  equal  to the  lesser  of
   eighty-five  percent  (85%) of the  closing  bid of the  Common  Stock on the
   Closing Date or seventy percent (70%) of the average closing bid price of the
   Common Stock for the five (5) NASDAQ Trading Days  immediately  preceding the
   Conversion  Date  (as  hereinafter  defined),  as  reported  by the  National
   Association  of Securities  Dealers  Automated  Quotation  System.  Provided,
   however,  that in no event shall the Conversion Price ever be less than $0.23
   per  share.  The  number of  Conversion  Shares to be  received  by Holder on
   conversion  shall  be the  product  of the  unpaid  principal  amount  of the
   Debenture  being  converted  divided by the Conversion  Price. On the Closing
   Date as defined in the Subscription Agreement, the Issuer will reserve on its
   books one  hundred  thousand  (100,000)  shares  of  Common  Stock for use in
   connection  with  conversion  of  this  Debenture.  The  Issuer  does  hereby
   irrevocably  agree to instruct  its  Transfer  Agent to provide  Common Stock
   Certificates  representing Conversion Shares to the Holder in accordance with
   the  terms of  conversion  hereinafter  set out.  Holder  shall  not sell any
   Conversion  Shares so converted until  forty-five (45) days after the Closing
   Date.  Such  conversion  by the  Holder  shall  be  effected  by  the  Holder
   surrendering to the Issuer this Debenture with the form of Conversion  Notice
   attached  hereto as Exhibit 1,  executed by the Holder of this  Debenture and
   accompanied,  if required by the Issuer, by proper assignment hereof in blank
   delivered  in the manner and time period as  hereinafter  set out. The Issuer
   shall then  instruct its  Transfer  Agent to deliver the  appropriate  Common
   Stock  Certificate  to the  Holder.  For  purposes  of  this  Debenture,  the
   "Conversion Date" shall be deemed to be the date on which the Holder has sent
   by facsimile the executed and  completed  Conversion  notice  together with a
   copy of this Debenture and any applicable  executed assignment to the Issuer.
   In order to convert,  this  Debenture  together with the Original  Conversion
   Notice duly  executed,  must be  delivered  by express  courier to the Issuer
   within Two (2) NASDAQ  Trading Days of the  Conversion  Date.  The Conversion
   Shares  must be issued and  returned by the  Transfer  Agent to the Holder by
   express courier with Five (5) NASDAQ Trading Days after the Conversion  Date.
   Accrued but unpaid interest shall, at the option of the Issuer, be subject to
   conversion under the terms and conditions  concerning the payment of interest
   set forth above at the time of  conversion  of this  Debenture or at the time
   any  quarterly  interest  payments  are due.  No  fractional  shares or scrip
   representing  fractional shares will be issued on conversion,  but the number
   of shares  issuable  shall be rounded to the nearest whole share.  The Issuer
   may, at its own option, cause the automatic conversion into Conversion Shares
   of the full unpaid amount of this  Debenture  after  February 15, 1998 at the
   aforesaid  Conversion  Price. The Issuer may exercise its option to cause the
   automatic conversion as set forth herein after said sixty (60) days notice to
   Holder  during  which sixty (60) days Holder may convert in  accordance  with
   Holder's conversion privileges  hereunder.  After the sixty (60) days and the
   exercise  of said  automatic  conversion,  Issuer may only  exercise  further
   automatic  conversion(s) in connection with not less than twenty-five percent
   (25%)  of  the  then  remaining  amounts  of  outstanding  Conversion  Shares
   pertaining to all of the unconverted  Debentures per automatic conversion and
   only after  thirty (30) days notice to Holder  during  which thirty (30) days
   Holder  may  convert  in  accordance  with  Holder's  conversion   privileges
   hereunder. The option shall be effectively exercised on the date on which the
   Issuer  transmits  by  facsimile   transmission  and  mails  notice  of  said
   conversion to the  registered  Holder of the effected  Debentures.  To effect
   such  conversion  by the  Issuer,  the  Conversion  Shares must be issued and
   delivered by the Transfer Agent to the Holder by express courier on or before
   the fifth (5th)  NASDAQ  Trading Day after the last day of such sixty (60) or
   thirty (30) day notice  period,  as the case may be, or the date on which the
   Holder  notifies  the Issuer  that the  Holder  elects  not to  exercise  the
   Holder's  conversion  privileges  hereunder.  Upon receipt of the  Conversion
   Shares and the payment (in cash or Common  Stock as herein  provided)  of any
   unpaid  interest,   the  Holder  shall  immediately  deliver  the  Debenture,
   appropriately  marked to indicate  payment in full thereof,  to the Issuer or
   its assignee pursuant to Issuer or its assignee's instructions.

5. No provision of this  Debenture  shall alter or impair the  obligation of the
   Issuer,  which is absolute and  unconditional,  to pay the  principal of, and
   interest on, this Debenture at the place,  time and rate, and in the coins or
   currency, herein prescribed.

6. The Issuer hereby expressly waives demand and presentment for payment, notice
   of  nonpayment,  protest,  notice of protest,  notice of dishonor,  notice of
   acceleration  or intent to  accelerate,  bringing  of suit and  diligence  in
   taking any  action to  collect  amounts  called  for  hereunder  and shall be
   directly  and  primarily  liable for the  payment of all sums owing and to be
   owing  hereon,  regardless  of and  without  any  notice,  diligence,  act or
   omission  as or with  respect  to the  collection  of any  amount  called for
   hereunder.

7. The  Issuer  agrees  to pay  all  cost  and  expenses,  including  reasonable
   attorneys' fees, which may be incurred by the Holder in collecting any amount
   due or exercising the conversion rights under this Debenture.



<PAGE>


8. If one or more of the following described "Events of Default" shall occur:

      (a)   The Issuer  shall  default in the payment of  principal  or interest
            on this Debenture; or

      (b)   Any of the  representations or warranties made by the Issuer herein,
            in the Subscription Agreement, or in any certificate or financial or
            other statements  heretofore or hereafter  furnished by or on behalf
            of the Issuer in connection  with the execution and delivery of this
            Debenture or the Subscription Agreement shall be false or misleading
            in any material respect at the time; or

      (c)   The Issuer shall fail to issue the  Conversion  Shares in accordance
            with  the  terms  of  conversion  set out in  Section  4 above or to
            perform or observe any other covenant,  term, provision,  condition,
            agreement or obligation of the Issuer under this  Debenture and such
            failure shall continue  uncured for a period of seven (7) days after
            notice from the Holder of such failure; or

      (d)   The Issuer  shall (1)  become  insolvent;  (2) admit in writing  its
            inability  to pay its debt  generally  as they  mature;  (3) make an
            assignment for the benefit of creditors or commence  proceedings for
            its dissolution; or (4) apply for or consent to the appointment of a
            trustee,  liquidator or receiver for it or for a substantial part of
            its property or business; or

      (e)   A trustee,  liquidator or receiver shall be appointed for the Issuer
            or a  substantial  part of its  property  or  business  without  its
            consent and shall not be  discharged  within  thirty (30) days after
            such appointment; or

      (f)   Any  governmental  agency or any court of competent  jurisdiction at
            the instance of any  governmental  agency  shall  assume  custody or
            control off the whole or any  substantial  portion of the properties
            or assets of the Issuer  and shall not be  dismissed  within  thirty
            (30) calendar days thereafter; or

      (g)   Bankruptcy,  reorganization,  insolvency or liquidation  proceedings
            or other  proceedings  for relief  under any  bankruptcy  law or any
            law for the  relief of  debtors  shall be  instituted  by or against
            the Issuer,  and if  instituted  against  the  Issuer,  shall not be
            dismissed  within thirty (30)  calendar days after such  institution
            or the Issuer  shall by any  action or answer  approve  of,  consent
            to, or  acquiesce  in any such  proceedings  or audit  the  material
            allegations  of, or default in  answering  a petition  filed in such
            proceeding; or

      (h)   The Issuer's Common Stock shall cease to be quoted on any of the New
            York  Stock  Exchange,  American  Stock  Exchange,   NASDAQ-National
            Market,  NASDAQ-Small  Cap or OTC  Electronic  Bulletin  Board for a
            period in excess of ninety (90) Calendar Days.

   Then, or at any time thereafter, and in each and every such case, unless such
   Event of  Default  shall have been  waived in  writing  by the Holder  (which
   waiver shall not be deemed to be a waiver of any  subsequent  default) at the
   option of the  Holder and in the  Holder's  sole  discretion,  the Holder may
   consider this Debenture  immediately  due and payable,  without  presentment,
   demand,  protest  or notice of any kind,  all of which are  hereby  expressly
   waived,  anything herein or in any note or other instruments contained to the
   contrary  notwithstanding,  and  the  Holder  may  immediately,  and  without
   expiration of any period of grace, enforce any and all of the Holder's rights
   and remedies provided herein or nay other rights or remedies afforded by law.

9. No recourse shall be had for the payment of the principal of, or the interest
   on, this  Debenture,  or for any claim based hereon,  or otherwise in respect
   hereof, against any incorporator,  shareholder, officer or director, as such,
   past, present or future, of the Issuer or any successor corporation,  whether
   by virtue of any  constitution,  statue or rule of law, or by  enforcement by
   any  assessment  or  penalty  or  otherwise,  all such  liability  being,  by
   acceptance  hereof  and as part of the  consideration  for the  issue  hereof
   expressly waived and released.

10.The Holder of this Debenture,  by execution of the Subscription Agreement and
   acceptance hereof agrees that this Debenture is being acquired for investment
   purposes and that such Holder will not offer,  sell or  otherwise  dispose of
   this debenture or the shares of Common Stock issuable upon conversion thereof
   except under  circumstances  which shall not result in a violation of the Act
   or any applicable  State Blue Sky law or similar laws relating to the sale of
   securities.

11.By  acceptance of this  Debenture,  the Holder hereby grants to the Issuer or
   its assignee the option ("Prepayment  Option"),  for a period beginning after
   February  15,  1998  to  repurchase  all of the  outstanding  portion  of the
   Debenture  plus  accrued  interest,  after  sixty (60) days  notice to Holder
   during which sixty (60) days Holder may convert in  accordance  with Holder's
   conversion privileges hereunder.  The repurchase price of this Debenture (the
   "Repurchase  Price") shall be equal to One Hundred and Five Percent (105%) of
   the full unpaid  principal  amount of the  Debenture,  plus accrued  interest
   payable in cash.  This  Prepayment  Option may be exercised by written notice
   via  telecopy  transmission  to  the  Holder  (with  written  notice  to  the
   registered address by overnight courier) after February 15, 1998 and delivery
   of the  Repurchase  Monies to the Holder on or before the fifth (5th)  NASDAQ
   trading  day after the last day of such sixty  (60) day notice  period or the
   date on which the Holder  notifies  the Issuer that the Holder  elects not to
   exercise the Holder's conversion  privileges  hereunder.  Upon receipt of the
   Repurchase   Monies,   Holder  shall   immediately   deliver  the  Debenture,
   appropriately  marked to indicate  payment in full thereof,  to the Issuer or
   its assignee pursuant to Issuer's or its assignee's instructions.

12.In  the  case  that  there  is  any  outstanding   amount  of  the  Debenture
   unconverted on March 25, 2000,  the  outstanding  unconverted  portion of the
   Debenture will be subject to automatic  conversion pursuant to the provisions
   of the last four sentences in Section 4 hereunder.

13.In case any  provision  of this  Debenture  is held by a court  of  competent
   jurisdiction to be excessive in scope or otherwise  invalid or  unenforceable
   such provision  shall be adjusted  rather than voided,  if possible,  so that
   such is  enforceable  to the maximum  extent  possible,  and the validity and
   enforceability of the remaining  provisions of this debenture will not in any
   way be affected or impaired thereby.

14.This  Debenture and the agreements  referred to in this Debenture  constitute
   the full and entire  understanding  and agreement  between the Issuer and the
   Holder with respect  hereof.  Neither this Debenture nor any terms hereof may
   be  amended,  waived,  discharged  or  terminated  other  than  by a  written
   statement signed by the Issuer and the Holder.

15.This  Debenture  shall be governed by and  construed in  accordance  with the
   laws of the state of Delaware and the United State of America.




<PAGE>


IN WITNESS  WHEREOF the Issuer has caused this instrument to be duly executed by
an officer thereunto duly authorized.

ISSUER:
NOISE CANCELLATION
TECHNOLOGIES, INC.



By:  /s/ STEPHEN J. FOGARTY
     Official Signatory of Issuer


Name (Printed:) Stephen J. Fogarty

Title:          Senior Vice-President and Chief Financial Officer

Date:           March 25, 1997


<PAGE>


                                    EXHIBIT 1
                              Notice of Conversion
  (To be executed by the Registered Holder in order to Convert the Debenture)

             TO:  Noise Cancellation Technologies, Inc.
                  One Dock Street
                  Stamford, Connecticut  06902
                  Attention:  John Horton, General Counsel
                  Fax:  (203) 348-4106
                  Tel:  (203) 961-0500 ext. 388

The  undersigned  (the  "Holder")  hereby  irrevocably  elects to convert  Fifty
Thousand  (USD  $50,000.00)  of  the  Debenture  No.___  of  NOISE  CANCELLATION
TECHNOLOGIES,  INC. (the "Issuer") according to the conditions set forth in such
Debenture,  as of the date  written  below.  The  shares are to be issued in the
"Street Name" written below:

The undersigned represents and warrants as follows:

(a)   The offer to convert the Debenture  was made to the Issuer  outside of the
      United States and the undersigned was, at the time the  subscription  form
      was executed and delivered, and is now outside the United States;

(b)   It is not a U.S.  person (as such term is  defined  in  Section  902(a) of
      Regulation  S  ("Regulation  S")  promulgated   under  the  United  States
      Securities Act of 1933 (the  "Securities  Act");  and it is converting the
      Debenture  for its own  account  and not for the account or benefit of any
      U.S. person;

(c)   All offers  and sales of the Common  Stock  shall be made  pursuant  to an
      effective  registration  statement under the Securities Act or pursuant to
      an exemption  from, or in a transaction  not subject to, the  registration
      requirements of the Securities Act;

(d)   It is  familiar  with  and  understands  the  terms  and  conditions,  and
      requirements  contained in Regulation S and  definitions  of U.S.  persons
      contained in Regulation S.

Holder:     OPTIMUM FUND (seal)


            By:__________________________
               Official Signatory of Holder

Title:______________________________ Country of Execution:____________


<PAGE>


Conversion Date (See Section 4)                 __________________
Closing Bid on the Closing Date (See Section 4) __________________
Average Closing Bid Price (See Section 4)       __________________
Conversion Price (See Section 4)                __________________
Number of common shares to be
received by Holder (see Section 4)              __________________


Name of Holder for Registration                 __________________

Address for Registration                        __________________

                                                __________________

"Street Name" for certificate                   __________________



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