**Exhibit 10.15****THIS PROMISSORY NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933. NO SALE ORDISPOSITION MAY BE AFFECTED EXCEPT IN COMPLIANCE WITH RULE 144 UNDER SAID ACT OR AN EFFECTIVEREGISTRATION STATEMENT RELATED THERETO OR AN OPINION OF COUNSEL FOR THE HOLDER, SATISFACTORY TO THECOMPANY, THAT SUCH REGISTRATION IS NOT REQUIRED UNDER THE ACT OR RECEIPT OF A NO-ACTION LETTER FROMTHE SECURITIES AND EXCHANGE COMMISSION.**PROMISSORY NOTE     $285,000.00 April 30, 2007  Durham, North Carolina     FOR VALUE RECEIVED, the undersigned (“Maker”), promises to pay to DIGITAL RECORDERS, INC.(“Payee”) at P. O. Box 14068, Research Triangle Park, NC 27709-4068, the principal sum of TwoHundred Eighty-Five Thousand Dollars and no/100 ($285,000.00), payable as follows:Principal shall be payable in four (4) equal annual installments of $71,250.00 each, withthe first payment due April 30, 2008 and subsequent payments due April 30, 2009, April 30,2010 and April 30, 2011. In addition, interest on the unpaid balance shall be paid insemi-annual installments at the prime rate of interest as published by the Wall StreetJournal on the date of its issuance, such rate to be adjusted on the anniversary date ofthis Promissory Note.     1. Subject to Offset. The obligation of Maker under this Note is subject tomodification, offset or reduction as set forth in Sections 2.2(a) and 9.2(c) of the Share PurchaseAgreement of even date herewith between Maker, Payee and Digital Audio Corporation.     2. Default. This note and all other obligations and liabilities of the Maker to thePayee shall become immediately due and payable without notice or demand upon the occurrence of anyof the following events with respect to Maker: filing of a voluntary or involuntary petition underany provision of the state or federal insolvency law (whether forbankruptcy, reorganization, arrangement, composition, extension, wage
 

 
earner’s plan, or otherwise); applicationfor or the appointment of a receiver; assignment for the benefit of creditors; entry of judgment orissuance of a warrant of attachment; appointment of a committee of creditors or a liquidatingagent, or calling of a meeting of creditors; or an offer of composition or extension to creditors,or a breach in the terms of the security agreement, or a default in payment of any installment duehereunder if such default is not cured within fifteen (15) days of written notice thereof.     3. Release and Modification. The Payee may renew or extend this note, release anyparty hereto, or waive or modify any provision hereof, without affecting the obligation of theMaker.     4. Right of Prepayment. Maker shall have the right to prepay this note at any timewithout penalty.     5. Captions. The use of captions in this note is for convenience only. Captions arenot intended to be used for, nor shall any caption be used in, the interpretation or constructionof this note.     6. Collection. In the event this note is not paid when due at any stated oraccelerated maturity, the Maker agrees to pay, in addition to the principal and interest, all costsof collection, including reasonable attorneys’ fees.         DOLPHIN DIRECT EQUITY PARTNERS, LP           By: Dolphin Advisors, LLC      Its managing general partner    By: Dolphin Management Inc.      Its managing member           By: /s/ Peter E. Salas     Name: Peter E. Salas    Title: President