A portable USB-based microphone array device for robust speech recognition

We present a USB-based, highly directional, and portable microphone array device that delivers a crisp, clear and noise-reduced speech signal. This device consists of four linearly distributed microphone sensors and a filter-and-sum beamformer designed using broadband beam-forming algorithm. The device has a narrow acoustic beam pattern and identical frequency responses for almost all speech bands. In addition to beamforming, an adaptive noise reduction algorithm is used to further reduce the background noise. By utilizing both the spatial and temporal information, the SNR of speech signals is improved and speech recognition performance in noisy environments is significantly improved as reported in our experiments.