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A novel method is proposed to improve the voice recognition performance by suppressing acoustic interferences that add nonlinear distortion to a target recording signal when received by the recognition device. The proposed method is expected to provide the best performance in smart TV environments, where a remote control collects command speech by the internal microphone and performs automatic voice recognition, and the secondary microphone equipped in a TV set provides the reference signal for the background noise source. Due to the transmission channel, the original interference is corrupted nonlinearly, and the conventional speech enhancement techniques such as beamforming and blind signal separation are not applicable. The proposed method first equalizes the interference in the two microphones by maximizing the instantaneous correlation between the nonlinearly related target recording and reference signal, and suppresses the equalized interference. To obtain an optimal estimation of the equalization filter, a method for detecting instantaneous activity of interference is also proposed. The validity of the proposed method is proved by the improvement in automatic voice recognition performance in a simulated TV room where loud TV sounds or babbling speech interfere in a user's commanding speech.
Date of Publication: February 2013