Abstract

A microphone array beamforming system is proposed for multimedia communication applications using four sets of small planar arrays mounted on a computer monitor. A new virtual array approach is employed such that the original signals received by the array elements are weighted and delayed to synthesize a large, nonuniformly spaced, harmonically nested virtual array covering the frequency band [50, 7000] Hz of the wideband telephony. Subband multirate processing and near-field beamforming techniques are then used jointly by the nested virtual array to improve the performances in reverberant environments. A new beamforming algorithm is also proposed using a broadband near-field spherically isotropic noise model for array optimization. The near-field noise model assumes a large number of broadband random noises uniformly distributed over a sphere with a finite radius in contrast to the conventional far-field isotropic noise model which has an infinite radius. The radius of the noise model, thus, adds a design parameter in addition to its power for tradeoffs between performance and robustness. It is shown that the near-field beamformers designed by the new algorithm can achieve more than 8-dB reverberation suppression while maintaining sufficient robustness against background noises and signal location errors. Computer simulations and real room experiments also show that the proposed array beamforming system reduces beampattern variations for broadband signals, obtains strong noise and reverberation suppression, and improves the sound quality for near-field targets.

Department(s)

Electrical and Computer Engineering

Keywords and Phrases

Acoustic Noise; Array Signal Processing; Beampattern Variation; Broadband Random Noise; Computer Monitor; Far-Field Isotropic Noise Model; Frequency Band; Interference Suppression; Microphone; Microphone Array Beamforming System; Microphone Array System; Microphone Arrays; Modeling; Multimedia Communication; Near-Field Beamforming; Near-Field Noise Model; Near-Field Signal Target; Reverberation; Reverberation Suppression; Signal Location Error; Speech Enhancement; Subband Multirate Processing; Virtual Array Approach; Wideband Telephony

International Standard Serial Number (ISSN)

1530-437X

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2005 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Full Text Link

Share

 
COinS