Speech enhancement using square microphone array for mobile devices

In this paper, we propose a new type of speech enhancement method that is suitable for mobile devices used in noisy environments. For the sake of achieving high-performance speech recognition and auditory perception in the mobile devices, disturbance noises have to be removed under the requirements of a space-saving microphone arrangement and a low computational cost. The proposed method can reduce both the directional and the diffuse noises under the requirements for the mobile devices by applying the square microphone array and the low-cost processing that consists of multiple null beam- forming, their minimum power channel selection and Wiener filtering. The effectiveness of the proposed method is clarified for speech recognition accuracies and speech qualities under the condition in which both the directional and the diffuse noises exist simultaneously: it reduced 40% of recognition errors and improved PESQ-based MOS value by 0.75 point.