Patent ID: 7908139
Filing Date: 2011-03-15
Classification: G10L

Abstract:
1. An apparatus for reducing a noise signal of a speech signal, the apparatus comprising an input unit receiving a speech signal including a noise signal: an estimation unit estimating a signal to noise ratio for each frequency band of a received speech signal; a control unit controlling noise reduction rates of the speech signal, based on the estimated signal to noise ratios for each frequency band; and a filter unit filtering the noise signal of the speech signal according to the controlled noise reduction rates, wherein the received speech signal is filtered by a determined gain factorization HGF of a Wiener filter expressed by the following equations: and wherein H(ω,t) is a noise suppressing Wiener filter, X(ω,t) is a spectrum of noisy input, Ñ(ω,t) is a current estimate of noise spectrum, ω is a frequency index, t is a frame index, a, b are SNR limits, a>b, ε is a small constant >0, α is a suppression rate parameter or a gain factorization constant.