On-line compensation for non-stationary noise

An improvement of a previously proposed frame-synchronous noise compensation algorithm is presented. The previous algorithm used the stochastic matching approach and was designed to cope with time-varying noise. The improved version of this algorithm takes into account the abrupt changes in the acoustical environment. The environment change is detected using the Shewart control charts detection algorithm that searches for the chances in the means of Gaussian sequence. For each noisy environment a specific mismatch function is estimated. A simple bias is used as mismatch function. After detection of environment change, the bias is reinitialized by the value corresponding to the closest noisy environment previously observed. This technique is general since no assumption is made on the nature, level and occurring time of noise. Our algorithm is evaluated on the VODIS database (speech in moving car). All the test sentences were corrupted by an additive noise occurring at the middle of each sentence. This latest version of our algorithm gives significant improvement compared to classical compensation algorithms.