Hoffman M W, Trine T D, Buckley K M, Van Tasell D J
Department of Electrical Engineering, University of Nebraska, Lincoln 68588-0511.
J Acoust Soc Am. 1994 Aug;96(2 Pt 1):759-70. doi: 10.1121/1.410313.
The problem of combining the outputs of an array of microphones as a single input for a hearing aid is investigated. Emphasis is placed on the conservative prediction of realistically achievable performance gains provided by the array over a single microphone. Performance improvement is measured as a change in the speech reception threshold (SRT) between single microphone and multimicrophone conditions. Consistent with previous work, predictions of this change in SRT using intelligibility averaged gain, [symbol: see text] are shown to be good. Consequently, this measure is used, along with changes in signal-to-noise ratios (SNRs), to evaluate array performance. The results presented include the effects of acoustic headshadow, small room reverberation, microphone placement uncertainty, and desired speaker location uncertainty. It is in this context that realistic predictions of speech enhancement provided by robust adaptive microphone array processors are discussed. Performance improvements are demonstrated relative to the "best" single microphone in the array for three types of spatial filters: Fixed, robust block processed, and robust adaptive. The performance of the robust block processed arrays is shown to be attainable with adaptive implementations. One fundamental criterion employed in robust beamformer design directly limits the amount of cancellation of the desired signal that can occur.
研究了将一组麦克风的输出组合作为助听器单一输入的问题。重点在于对该阵列相对于单个麦克风实际可实现的性能增益进行保守预测。性能提升以单麦克风和多麦克风条件下语音接收阈值（SRT）的变化来衡量。与先前的工作一致，使用清晰度平均增益[符号：见原文]对SRT的这种变化进行的预测显示是良好的。因此，该度量与信噪比（SNR）的变化一起用于评估阵列性能。给出的结果包括声头影、小房间混响、麦克风放置不确定性以及期望扬声器位置不确定性的影响。正是在这种背景下，讨论了稳健自适应麦克风阵列处理器提供的语音增强的实际预测。相对于阵列中的“最佳”单个麦克风，展示了三种类型空间滤波器的性能提升：固定型、稳健块处理型和稳健自适应型。结果表明，稳健块处理阵列的性能可以通过自适应实现来达到。稳健波束形成器设计中采用的一个基本准则直接限制了可能发生的期望信号抵消量。
