Computer-steered microphone arrays for sound transduction in large rooms

Abstract

The quality of sound pickup in large rooms—such as auditoriums, conference rooms, or classrooms—is impaired by reverberation and interfering noise sources. These degradations can be minimized by a transducer system that discriminates against sound arrivals from all directions except that of the desired source. A two-dimensional array of microphones can be electronically beam-steered to accomplish this directivity. This report gives the theory, design, and implementation of a microprocessor system for automatically steering a two-dimensional microphone array. The signal-seeking transducer system is implemented as a dual-beam ‘‘track-while-scan’’ array. It utilizes signal properties to distinguish between desired speech sources and interfering noise.

Epoch-based analysis of speech signals

“…When speech is transmitted in an acoustical environment similar to an office room, it will be degraded by background noise and reverberation (Boll 1979;Cheng & O'Shaughnessy 1991;Ephraim & Trees 1995;Flanagan et al 1985;Huang & Zhao 1998;Jensen & Hansen 2001;Mittal & Phamdo 2000;Miyoshi & Kaneda 1988;Nemer et al 2002;Oh & Viswanathan 1992;Satyanarayana 1999;Scalart & Benmar 1996;Silverman 1987;Subramaniam et al 1996;Yegnanarayana et al 1997Yegnanarayana et al , 1999Yegnanarayana & Murthy 2000). Multichannel case is more effective for enhancement compared to the single channel case, but requires estimation of timedelays (Flanagan et al 1985).…”

“…Multichannel case is more effective for enhancement compared to the single channel case, but requires estimation of timedelays (Flanagan et al 1985). A simple method for enhancement in multichannel case is addition of the speech signals, after compensating for the delays.…”

Acoustic robot navigation using distributed microphone arrays

“…These time differences and intensity differences can be used to localize the sound source location [1][2][3][4]7,13,14]. In practice, due to the presence of reverberations, the TDOAs are more reliable for sound source localization, and hence are commonly used as the primary basis for source localization.…”

α-Jacobian environmental adaptation

“…Review of noise robust methods for automatic speech recognition 1.3.1. General review A first set of methods to deal with background noise separates the noise from the speech signal (Flanagan et al, 1985), but these algorithms usually make use of two or more microphones and assume that the noise source is far from the speech source. It is then possible to use stereophonic effects to separate the two sound sources.…”