WAIVER, CONSENT AND FOURTH AMENDMENT AGREEMENT

Exhibit 10.43

WAIVER, CONSENT AND FOURTH AMENDMENT AGREEMENT

This WAIVER, CONSENT AND FOURTH AMENDMENT AGREEMENT (this “Agreement”) is entered into as of this 6th day of March, 2006, by and among Digital Recorders, Inc., Digital Audio Corporation and TwinVision of North America, Inc. (collectively, “Borrowers”) and LaSalle Business Credit, LLC (“LaSalle”). Unless otherwise specified herein, capitalized terms used in this Agreement shall have the meanings ascribed to them in the Loan Agreement (as hereinafter defined).

RECITALS

WHEREAS, the Borrowers and LaSalle are parties to that certain Loan and Security Agreement dated as of November 6, 2003, (as amended, the “Loan Agreement”);

WHEREAS, an Event of Default occurred under Section 15(b) of the Loan Agreement as a result of the Borrowers’ failure to maintain the required EBITDA to Fixed Charge ratio for the 12-month period ended December 31, 2005 (the “Existing Default”);

WHEREAS, the Borrowers have requested that LaSalle waive the Existing Default and amend the Loan Agreement upon the terms and conditions set forth herein; and

WHEREAS, LaSalle has agreed to waive the Existing Default and amend the Loan Agreement on the terms and conditions set forth herein.

NOW, THEREFORE, in consideration of the mutual execution hereof and other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the parties hereto agree as follows:

SECTION 1. Limited Consent. In the event the Borrowers receive the cash equity infusion described in Section 6 hereof on or prior to March 21, 2006, notwithstanding anything in the Loan Agreement to the contrary, absent the occurrence and continuance of an Event of Default other than the Existing Default, the Borrowers may deposit such cash in their disbursement account at Wachovia Bank and utilize such cash to pay their ordinary course expenses.

SECTION 2. Limited Waiver of LaSalle. LaSalle hereby waives the Existing Default.

SECTION 3. Amendments to Loan Agreement. The parties agree to amend the Loan Agreement as set forth in this Section 2.

(a) Section 2(a) of the Loan Agreement is hereby amended by deleting the clause (iv) and the proviso at the end of the first paragraph thereof and replacing them with the following:

(iv) such reserves as Lender elects, in its sole discretion determined in good faith, to establish from time to time, including, without limitation, a reserve of One Million Two Hundred Thousand and No/100 |CH\828654.1||

Dollars ($1,200,000.00) plus an additional Ten Thousand and No/100 Dollars ($10,000.00) per week on Friday of each week, beginning with the week ended Friday, March 3, 2006;

provided, that (x) the sum of the advances to all Borrowers with respect to clauses (ii) and (iii) above shall at no time exceed Three Million Five Hundred Thousand and No/100 Dollars ($3,500,000.00) and (y) the Revolving Loan Limit shall in no event exceed Three Million Eight Hundred Thousand and No/100 Dollars ($3,800,000.00) less the then- outstanding principal balance of the Term Loan (the “Maximum Revolving Loan Limit”) except as such amount may be increased or decreased by Lender, in its sole discretion.

(b) Section 4(a) of the Loan Agreement is hereby amended by deleting the first sentence thereof and replacing it with the following: Each Loan shall bear interest at the rate of three and three quarters percent (3-3/4%) per annum in excess of the Prime Rate in effect from time to time, payable on the last Business Day of each month in arrears.

(c) Section 10 of the Loan Agreement is hereby amended by deleting such Section in its entirety and replacing it with the following:

10. TERMINATION.

THIS AGREEMENT SHALL BE IN EFFECT FROM THE DATE HEREOF UNTIL JUNE 30, 2006 (THE “ORIGINAL TERM”) UNLESS ACCELERATED PURSUANT TO SECTION 16 HEREOF. If the term of this Agreement expires, then (i) Lender shall not make any additional Loans on or after the date identified as the date on which the Liabilities are to be repaid; and

(ii) this Agreement shall terminate on the date thereafter that the Liabilities are paid in full. At such time as Borrowers have repaid all of the Liabilities and this Agreement has terminated, each Borrower shall deliver to Lender a release, in form and substance satisfactory to Lender, of all obligations and liabilities of Lender and its officers, directors, employees, agents, parents, subsidiaries and affiliates to such Borrower, and if such Borrower is obtaining new financing from another lender, such Borrower shall deliver such lender’s indemnification of Lender, in form and substance satisfactory to Lender, for checks which Lender has credited to such Borrower’s account, but which subsequently are dishonored for any reason or for automatic clearinghouse or wire transfers not yet posted to such Borrower’s account. If, during the term of this Agreement, Borrowers prepay all of the Liabilities from any source other than income from the ordinary course operations of Borrower’s business and this Agreement is terminated, Borrowers jointly and severally agree to pay to Lender as a prepayment fee, in addition to the payment of all other Liabilities, an amount equal to (i) three percent (3%) of the Maximum Loan Limit if such prepa