LMS Adaptive filtering for enhancing the quality of noisy speech

A linear mean square (LMS) adaptive filtering approach has been formulated for removing the deleterious effects of additive noise on the speech signal; Unlike the classical LMS adaptive filtering scheme, the proposed method is designed to cancel out the clean true speech signal. This method takes advantage of the quasi-periodic nature of the speech signal to form an estimate of the clean speech signal at time t from the value of the signal at time t minus the estimated pitch period. For additive white noise distortion, preliminary tests indicate that the method improves the perceived speech quality and increases the signal to noise ratio (SNR) by 7 db in a 0 db environment. The method has also been preliminarily shown to remove the perceived granularity of CVSD coded speech signals and to lead to an improvement in the linear prediction analysis/synthesis of noisy speech.