A directionally tunable but frequency-invariant beamformer on an acoustic velocity-sensor triad to enhance speech perception

Abstract

Herein investigated are computationally simple microphone-array beamformers that are independent of the frequency-spectra of all signals, all interference, and all noises. These beamformers allow the listener to tune the desired azimuth-elevation "look direction." No prior information is needed of the interference. These beamformers deploy a physically compact triad of three collocated but orthogonally oriented velocity sensors. These proposed schemes' efficacy is verified by a jury test, using simulated data constructed with Mandarin Chinese (a.k.a. Putonghua) speech samples. For example, a desired speech signal, originally at a very adverse signal-to-interference-and-noise power ratio (SINR) of -30 dB, may be processed to become fully intelligible to the jury.

Characterization and modeling of CMOS-compatible acoustical particle velocity sensors for applications requiring low supply voltages

“…By measuring sound velocity instead of pressure is thus straightforward to extract the sound direction of arrival (DOA). This is very useful, just to name a few applications, for sound source localization [2,3] and beam-forming [4,5]. An important case that, in the near future, might justify mass production of DOA detectors is constituted by systems designed to individuate humans requesting attention with vocal commands in order, for example, to steer a video camera in teleconferences or guide a robot for disabled person assistance.…”

“…This solution, however, cannot be arbitrarily miniaturized due to constraints on the distances between the microphones. Furthermore it is intrinsically narrow-banded and requires strict sensor matching [5,6,7]. For these reasons, over the last few years there has been quite some interest in the development of acoustic particle velocity (APV) sensors; the first effective implementation was proposed by de Bree et al [8,9], and was based on forced thermal convection between two heated wires.…”

An Hybrid Cramér-Rao Bound in Closed Form for Direction-of-Arrival Estimation by an “Acoustic Vector Sensor” With Gain-Phase Uncertainties

“…Apply (35) to the 6 6 matrix , (36) where are non-negative integers , and is a polynomial in , and/or . The abovementioned double inequality of apply, because only the first three rows (among the six rows of ) have non-zero terms involving none of and .…”

“…The six preceding formulas are obtained by using (35) and by collecting terms of the corresponding forms.…”

“…For a literature survey of the acoustic vector sensor's directivity and beam-pattern, please refer to [35].…”