In close-talking applications, such as mobile phones, selective measurement of the near-field sound is desirable as it can be used to improve the signal-to-noise ratio. In this study, the theory of generalized radiation modes is applied to the design of microphone arrays. The generalized radiation modes are formulated as a generalized eigenvalue problem related to the specific acoustic impedances on the array surface. The real eigenvalue corresponds to the near-to-far ratio for each mode and the real eigenvector indicates the modal shape, i.e., the amplitudes and phases of the individual microphones. The microphone array is designed according to the eigenvector with the largest eigenvalue so as to maximize the near-to-far ratio. The theory is verified based on computer simulations. The proposed method is also compared with conventional gradient microphones via numerical examples.

中文翻译：

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用于近距离通话的广义辐射模式和麦克风阵列

在移动电话等近距离通话应用中，需要对近场声音进行选择性测量，因为它可以用来提高信噪比。本研究将广义辐射模式理论应用于麦克风阵列的设计。广义辐射模式被表述为与阵列表面上的特定声阻抗相关的广义特征值问题。实特征值对应于每个模式的远近比，实特征向量表示模态形状，即各个麦克风的幅度和相位。麦克风阵列根据特征值最大的特征向量进行设计，使近远比最大化。该理论基于计算机模拟得到验证。