September 22-25, 1997
This paper proposes a front-end method for enhancing the target signal by subtracting estimated noise from a noisy signal using paired microphones, assuming that the noise is unevenly distributed with regard to time, frequency, and the direction. Although the Griffiths- Jim type adaptive beamformer has been proposed using the same concept, this method has some drawbacks. For example, sudden noises cannot be reduced because the convergence speed of the adaptive filter is slow; also the signal is distorted in a reverberated environment. The proposed method, however, can over-come the above drawbacks by formulating noises using arrival time differences between paired microphones and by estimating noises analytically using the directions of the noises. The simulated results show that the method with one paired microphone can increase signal-to-noise ratios (SNR) by 10 ~ 20 dB in simulations and can reduce log-spectrum distances by about 5 dB in real noisy environments.
Bibliographic reference. Akagi, Masato / Mizumachi, Mitsunori (1997): "Noise reduction by paired microphones", In EUROSPEECH-1997, 335-338.