Robust Generalized Sidelobe Canceller Research Articles

A 650-μW 4-Channel 83-dBA-SNDR Speech Recognition Front-End With Adaptive Beamforming and Feature Extraction

A speech recognition front-end combines a four-channel adaptive beamformer and a 40-feature Mel frequency extractor. The prototype processes the bitstream outputs of third-order delta–sigma modulators with a robust generalized sidelobe canceller (RGSC) for accurate steering. For a given steering vector, the beamformer adaptively places a null in the direction of the noise. Hardware sharing and DSP clock optimization reduce area and power consumption. The prototype is fabricated in 40-nm CMOS and occupies an active area of 0.89 mm2. The prototype beamformer improves speech recognition accuracy in noisy conditions from 64% to 90%.

Robust generalized sidelobe canceller based on eigenanalysis and a MaxSINR beamformer

A robust generalized sidelobe canceller is proposed to combat direction of arrival (DOA) mismatches. To estimate the interference-plus-noise (IPN) statistics characteristics, conventional signal of interest (SOI) extraction methods usually collect a large number of segments where only the IPN signal is active. To avoid that collection procedure, we redesign the blocking matrix structure using an eigenanalysis method to reconstruct the IPN covariance matrix from the samples. Additionally, a modified eigenanalysis reconstruction method based on the rank-one matrix assumption is proposed to achieve a higher reconstruction accuracy. The blocking matrix is obtained by incorporating the effective reconstruction into the maximum signal-to-interferenceplus- noise ratio (MaxSINR) beamformer. It can minimize the influence of signal leakage and maximize the IPN power for further noise and interference suppression. Numerical results show that the two proposed methods achieve considerable improvements in terms of the output waveform SINR and correlation coefficients with the desired signal in the presence of a DOA mismatch and a limited number of snapshots. Compared to the first proposed method, the modified one can reduce the signal distortion even further.

Robustness analysis of multichannel Wiener filtering and generalized sidelobe cancellation for multimicrophone noise reduction in hearing aid applications

For small-sized arrays such as hearing aids, noise reduction is obtained at the expense of an increased sensitivity to errors in the assumed signal model, i.e., microphone mismatch, variations in speaker and microphone positions, reverberation. However, the noise reduction algorithm should still be robust, i.e., insensitive to small signal model errors. In this paper, we evaluate the robustness of the Generalized Sidelobe Canceller (GSC) and a recently developed Multichannel Wiener Filtering (MWF) technique for hearing aid applications both analytically and experimentally. The analysis reveals that robustness of the GSC is especially crucial in complicated noise scenarios and that microphone mismatch is particularly harmful to the GSC, even when the adaptive noise canceller is adapted during noise only. Hence, a constraint on the noise sensitivity of the GSC is essential, at the expense of less noise reduction. The MWF on the other hand, is not affected by microphone mismatch and has a potential benefit over the robust GSC with noise sensitivity constraint. However, the MWF is sensitive to the estimation accuracy of the second order statistics of speech and noise so that its benefit may be lost in nonstationary noise scenarios.

An Acoustic Human-Machine Front-End for Multimedia Applications

A concept of robust adaptive beamforming integrating stereophonic acoustic echo cancellation is presented which reconciles the need for low-computational complexity and efficient adaptive filtering with versatility and robustness in real-world scenarios. The synergetic combination of a robust generalized sidelobe canceller and a stereo acoustic echo canceller is designed in the frequency domain based on a general framework for multichannel adaptive filtering in the frequency domain. Theoretical analysis and real-time experiments show the superiority of this concept over comparable time-domain approaches in terms of computational complexity and adaptation behaviour. The real-time implementation confirms that the concept is robust and meets well the practical requirements of real-world scenarios, which makes it a promising candidate for commercial products.

A robust generalized sidelobe canceller with a blocking matrix using leaky adaptive filters

A new robust generalized sidelobe canceller structure suited to adaptive microphone arrays is proposed. In the proposed structure, the blocking matrix incorporates leaky adaptive filters whose input signals are the output of the fixed beamformer. The leaky adaptive filters alleviate the influence of phase error, which results in the robustness. Undesirable target-signal cancellation is avoided in the presence of array imperfections such as target-direction error and microphone-position error. The proposed structure can pick up a target signal with little distortion when the error in the sight direction from the target direction is large. It can be implemented with a small number of microphones. Simulations demonstrate that the proposed structure, designed to allow 20° directional error, reduces interference by more than 18 dB. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 3, 80(8): 56–65, 1997