Differential microphone arrays (DMAs), which are responsive to the differential acoustic pressure fields, have been used in a wide range of applications related to audio and speech. The core part of a DMA is the so-called differential beamformer, which is generally designed by placing a number of nulls in its beampattern to attenuate noise from some directions. But the presence of these nulls may cause some great issues, e.g., leading to suboptimal performance if the interference/noise is incident from directions other than the nulls’ directions, and making the beamformer less robust to sensors’ self noise and array imperfections. To overcome these problems, this letter is devoted to the design of differential beamformers with no nulls in its beampattern. A design method and its multistage implementation are presented and analyzed. An improved solution is then developed, which is able to form frequency-invariant beampatterns with no nulls in the frequency range of speech signals. Simulations are provided to illustrate the properties of the developed methods.

中文翻译：

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具有类似心形和无零点模式的特定差分波束形成器系列

差分麦克风阵列 (DMA) 可响应差分声压场，已广泛用于与音频和语音相关的应用中。DMA 的核心部分是所谓的差分波束成形器，其设计通常是通过在其波束图中放置多个零点来衰减来自某些方向的噪声。但是这些零点的存在可能会导致一些严重的问题，例如，如果干扰/噪声从零点方向以外的方向入射，则会导致性能欠佳，并使波束形成器对传感器自身噪声和阵列缺陷的鲁棒性降低。为了克服这些问题，这封信致力于设计波束图中没有零点的差分波束形成器。提出并分析了一种设计方法及其多级实现。然后开发了一种改进的解决方案，它能够形成频率不变的波束图，在语音信号的频率范围内没有零点。提供了模拟来说明所开发方法的特性。