Abstract: A real-time passive acoustic source localization system for video camera steering advantageously determines the relative delay between the direct paths of two estimated channel impulse responses. The illustrative system employs an approach referred to herein as the “adaptive eigenvalue decomposition algorithm” (AEDA) to make such a determination, and then advantageously employs a “one-step least-squares algorithm” (OSLS) for purposes of acoustic source localization, providing the desired features of robustness, portability, and accuracy in a reverberant environment. The AEDA technique directly estimates the (direct path) impulse response from the sound source to each of a pair of microphones, and then uses these estimated impulse responses to determine the time delay of arrival (TDOA) between the two microphones by measuring the distance between the first peaks thereof (i.e., the first significant taps of the corresponding transfer functions).

Abstract: A first-order differential microphone array with a fully steerable and variable response pattern. One illustrative embodiment of the present invention comprises a microphone array consisting of 6 small pressure-sensitive omnidirectional microphones flush-mounted on the surface of a 3/4" diameter rigid nylon sphere. The microphones are advantageously located on the surface at points where included octahedron vertices contact the spherical surface. By selectively combining the three Cartesian orthogonal pairs with scalar weightings, a general first-order differential microphone beam (or a plurality of beams) is realized which can be directed to any angle (or angles) in three-dimensional space. The microphone array may find use in surround sound recording/playback applications and in virtual reality audio applications.

Abstract: An acoustic transducer including an acoustical reflecting surface of a finite dimension and at least one sensor having an output which produces a first-order differential response pattern. The sensor is located proximate to the reflecting surface, wherein acoustical waves propagating from the reflecting surface, acoustically interact with the sensor to produce a second-order differential response pattern at the output of the sensor at a predetermined frequency. The second-order differential response pattern at the output of the sensor occurs at the predetermined frequency when the finite dimension of the reflecting surface is at least one-half of an acoustic wavelength.