Registration Rights Agreement

EXHIBIT 10.15

FINAL

REGISTRATION RIGHTS AGREEMENT

This REGISTRATION RIGHTS AGREEMENT (the " Agreement" ), made as of the 27th of April, 2005 (the " Effective Date" ), by and between American Technology Corporation, a Delaware Corporation (" ATC" or the " Company" ) on the one hand, and Greg O. Endsley, an individual (" Endsley" ), Douglas J. Paschall, an individual (" Paschall" ) and Gordon & Holmes LLP, a California limited liability partnership (" Gordon & Holmes" ), on the other hand, is made with reference to the following facts. Endsley, Paschall and Gordon & Holmes are referred to collectively as the " Investors."

R E C I T A L S

A. ATC, Endsley, Paschall and certain other parties entered into an Agreement of Settlement and Mutual Release on the Effective Date (the " Settlement Agreement" ), pursuant to which ATC agreed to issue the aggregate of Seventeen Thousand Five Hundred (17,500) shares (the " Shares" ) of ATC common stock, $0.00001 par value (" Common Stock" ), to be divided as follows: 8,750 shares to Endsley and 8,750 shares to Paschall; provided that each of Endsley and Paschall instructed ATC to cause 3,500 shares of his shares (for a total of 7,000 share) to be issued in the name of Gordon & Holmes as compensation for legal fees incurred by the ESI Parties in the defense and prosecution of the claims described in the Settlement Agreement The share certificates issued by ATC were therefore to be in the following denominations: Endsley 5,250 shares Paschall 5,250 shares Gordon & Holmes 7,000 shares

B. ATC desires to grant the Investors certain rights with respect to the registration of the Shares, subject to the conditions as set forth herein.

A G R E E M E N T

In consideration of the foregoing and the promises and covenants contained herein and other good and valuable consideration the receipt of which is hereby acknowledged, the parties hereto agree as follows:

1. Definitions . For the purposes of this Agreement:

1.1 " Registrable Securities" shall mean (i) the Shares and (ii) shares of Common Stock which may be issued hereafter to the Investors with respect to the Shares in consequence of any additional issuance, exchange or reclassification of the Common Stock, corporate reorganization or any other form of recapitalization, consolidation or merger; provided, however, that Registrable Securities shall not include any such securities sold by the Investors to the public either pursuant to a registration statement or Rule 144 or sold in a private transaction.

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1.2 " Rule 144" shall mean Rule 144 promulgated under the Securities Act.

1.3 " Securities Act" shall mean the Securities Act of 1933, as amended.

1.4 " SEC" shall mean the Securities and Exchange Commission.

1.5 " Securities Exchange Act" shall mean the Securities Exchange Act of 1934, as amended.

2. Piggyback Registration . If the Company shall at any time or times determine to file a registration statement under the Securities Act for any shares of its Common Stock other than (i) registration statements on Forms S-4, S-8 or any successor to such forms, (ii) another form not available for registering the Registrable Securities for sale to the public or any registration statement including only securities issued pursuant to a dividend reinvestment plan, or (iii) a registration statement in which the only securities to be registered are securities issuable upon conversion of debt securities or other convertible securities which are also being registered, the Company will notify the Investors in each case of such determination at least ten (10) days prior to filing the registration statement and, upon the receipt of the Investors' written request given within five (5) days after the Investors' receipt of such notification, the Company will use its best efforts to cause any of the Registrable Securities, as specified in such request, to be registered under the Securities Act pursuant to such registration statement, to the extent and under the condition that such registration is permissible under the Securities Act and the rules and regulations thereunder. The Company shall have the right to terminate or withdraw any registration initiated by it prior to the effectiveness of such registration whether or not any of the Investors has elected to include securities in such registration. The Registration Expenses of such withdrawn registration shall be borne by the Company in accordance with Section 4 hereof.

3. Underwriting . In connection with any offering involving an underwriting of shares of the Company' s capital stock, the Company shall not be required under Section 2 to include any of the Registrable Securities of the Investors in such underwriting unless they accept the terms of the underwriting as agreed upon between the Company and the underwriters selected by it, and then only in such quantity as the underwriters determine in their sole discretion will not jeopardize the success of the offering by the Company.

4. Expenses . The Company shall pay all expenses incurred in connection with any registration pursuant to this Agreement; provided, that the Investors shall pay for (i) any brokerage or underwriting commissions or discounts relating to Common Stock sold by the Investors, and (ii) fees of counsel to the Investors.

5. Information Supplied by the Investors . In connection with any registration pursuant to this Agreement, the Investors shall furnish the Company with such information or documents as the Company may reasonably request and as shall be required by all applicable provisions of the Securities Act and the rules and regulations thereunder.

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6. Indemnification . In the event any Registrable Securities are included in a registration statement under this Agreement:

6.1 To the extent permitted by law, the Company will indemnify and hold harmless the Investors, any underwriter (as defined in the Securities Act) for the Investors and each person, if any, who controls the Investors or underwriter within the meaning of the Securities Act or the Securities Exchange Act, agai ...