Noise estimation techniques for robust speech recognition

Two new techniques are presented to estimate the noise spectra or the noise characteristics for noisy speech signals. No explicit speech pause detection is required. Past noisy segments of just about 400 ms duration are needed for the estimation. Thus the algorithm is able to quickly adapt to slowly varying noise levels or slowly changing noise spectra. This techniques can be combined with a nonlinear spectral subtraction scheme. The ability can be shown to enhance noisy speech and to improve the performance of speech recognition systems. Another application is the realization of a robust voice activity detection