Adaptive microphone array system for noise reduction (AMNOR) and its performance studies

The author describes the principle and performance of AMNOR, which consists of a compact microphone array and signal processing techniques that include an adaptive filter. It achieves high-SNR (signal-to-noise) sound reception, which is essential in areas such as teleconference systems and speech-recognition systems. The basic distinction of AMNOR compared to previous designs is that it realizes higher SNR by accepting some degree of degradation of a desired speech signal. A noise power minimization problem under second-order constraints is solved in the AMNOR system using an adaptive filter. An experiment conducted in an ordinary room showed that AMNOR realized a 21-dB SNR improvement, while a conventional directional microphone attained a 3-dB SNR improvement.<
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