A subband noise-reduction method for enhancing speech in telephony and teleconferencing

An algorithm is presented for reducing stationary, though possible changing, background noise in speech time series. A perfect reconstruction filter bank decomposes full-band time series into uniformly spaced subbands. A detection test is performed in each subband, and the results are used to dynamically adjust the gain applied to each subband. Upon reconstruction of the full-band time series, the background noise level is reduced relative to the speech. For many applications, 12 to 18 dB of noise reduction can be achieved in real-world settings. The method is demonstrated using examples of both telephony grade (narrowband) and teleconferencing grade (wideband) speech. As demonstrated using standard speech coders, the method can dramatically enhance the quality of coded speech.