Improved Close Air Support Effectiveness Through a Noise Cancellation Device Navy SBIR FY2009.1 Sol No.: Navy SBIR FY2009.1 Topic No.: N091-024 Topic Title: Improved Close Air Support Effectiveness Through a Noise Cancellation Device Proposal No.: N091-024-0769 Firm: Acentech Incorporated 33 Moulton Street Cambridge, Massachusetts 02138 Contact: David Bowen Phone: (617) 499-8068 Web Site: www.acentech.com Abstract: The rejection of transient and broadband gunshot noise signals in the presence of speech has the problem that speech is also transient and broadband. Although adaptive filtering and/or matched filter rejection will have some application, additional characteristics that separate gunfire from speech are needed for optimal noise cancellation. This proposal is based on those two features - the difference in directions of gunfire and the talker relative to the handset microphone, and on the closer proximity of the talker relative to the sources of gunfire. These additional features are basic to the proposed approach that uses new, patented technology. This new technology, termed PrivacyFone, employs a small microphone array that emphasizes the talker's voice signal by taking advantage of the fact that the array is in the near field (acoustic induction field) of the speech and not in the near field of the gunfire. The same array also rejects signals from directions associated with the gunfire. These features, basic to PrivacyFone, provide a way to discriminate against gunfire and enhance the speech signal. Any remnant of environmental noise that remains in the transmitted signal is then further rejected by an adaptive filtering scheme. Benefits: The commercial applications of the technology that is basic to this proposal are nearly unbounded. PrivacyFone has potential to change the way cell phones are used, by reducing background noise and the amount of speech sound that can annoy bystanders. Any situation in which noise rejection and privacy is desired, such as the recording of speech in a courtroom, can make direct use of the patented PrivacyFone technology. Military, security, and homeland defense operatives sometimes need to communicate in noisy environments, sometimes clandestinely in quiet environments. PrivacyFone and the approach outlined in this proposal can support both of these needs. Return