Abstract The performance of adaptive beamformers may suffer from significant degradation in the presence of steering vector errors, statistics estimation errors, and reverberation. To address this issue, robust beamforming methods, which were originally studied in the narrow-band cases, are studied and compared in this paper for processing acoustic and speech signals, which are broadband in nature. We study two types of methods. In the first type, the robustness of the beamformer is improved by adding a norm constraint and/or a steering vector uncertainty constraint to the optimization problem. It is worth noticing that the norm constraint also helps to control the sidelobes of the beampattern, which makes the beamformers able to suppress interference and multipath effect, thereby improving the robustness of the beamformers with respect to reverberation. Another type of methods improve the robustness using the spatial smoothing technique in which the noise covariance matrix is implicitly estimated first by subtracting an estimate of the desired signal covariance matrix with a delay-and-sum beamformer from the observation signal covariance matrix. Simulations and experiments are performed to investigate the performance of the studied robust adaptive beamformers in acoustic environments. The results show that the robust beamformers outperform their non-robust counterparts in terms of: (1) better performance in reverberation and different noise levels; (2) resilience against steering vector and noisy signal covariance matrix estimation errors; and (3) better predicted speech quality and intelligibility measured using the PESQ and STOI measures.

中文翻译：

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混响噪声环境下语音采集的鲁棒声波束形成实验研究

摘要 自适应波束成形器的性能可能会因存在导向向量误差、统计估计误差和混响而显着下降。为了解决这个问题，本文研究和比较了最初在窄带情况下研究的鲁棒波束成形方法，用于处理本质上是宽带的声学和语音信号。我们研究两种类型的方法。在第一种类型中，通过向优化问题添加范数约束和/或导向向量不确定性约束来提高波束形成器的鲁棒性。值得注意的是，范数约束还有助于控制波束图的旁瓣，这使得波束形成器能够抑制干扰和多径效应，从而提高波束形成器在混响方面的鲁棒性。另一类方法使用空间平滑技术来提高鲁棒性，其中首先通过从观测信号协方差矩阵中减去具有延迟求和波束形成器的期望信号协方差矩阵的估计值来隐式估计噪声协方差矩阵。进行模拟和实验以研究所研究的鲁棒自适应波束形成器在声学环境中的性能。结果表明，鲁棒波束形成器在以下方面优于非鲁棒波束形成器：(1) 更好的混响性能和不同的噪声水平；(2) 抗导向向量和噪声信号协方差矩阵估计误差的弹性；