This paper proposes a near-field broadband adaptive beamforming scheme for intelligent computer telephony and teleconferencing applications, namely the nested microphone array with adaptive noise canceller (NMA-ANC). The NMA-ANC scheme incorporates an harmonically nested array with a nonuniformly subbanded multirate filter bank. Each subband array employs several near-field delay-filter-and-sum beamformers and an adaptive noise canceller (ANC). The proposed NMA-ANC is evaluated via a noise rejection experiment and dereverberation experiment performed in an anechoic chamber and a real conference room, respectively. The experiment data are recorded by a multichannel digital recording system developed using commercial off-the-shelf (COTS) equipments. A perceptual analysis/measurement system (PAMS) test is also carried out using a COTS digital speech level analyzer. The results of the experimental evaluation and PAMS test show that the proposed NMA-ANC scheme is able to improve the sound quality by adaptively rejecting multiple interfering signals and attenuating the reverberant noises and avoiding the desired signal cancellation.

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Keywords Adaptive noise canceller, Broadband beamforming, Dereverberation, Interface rejection, Multichannel digital recording, Near-field beamforming, Nested microphone array (NMA), Subband multirate systems
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Journal IEEE Transactions on Instrumentation and Measurement
Zheng, Y.R. (Yahong R.), Goubran, R, & El-Tanany, M. (2004). Experimental evaluation of a nested microphone array with adaptive noise cancellers. IEEE Transactions on Instrumentation and Measurement, 53(3), 777–786. doi:10.1109/TIM.2004.827304