Three-stage hybrid system for speech signal enhancement

The objective of speech enhancement is to improve the quality and intelligibility of the speech. The goal of this paper is to propose a technique to eliminate the background noise of actual environment in speech processing system. The proposed hybrid speech enhancement method combines both the spectral subtraction algorithm and the conventional Wiener filtering in series with a band pass filter to construct a three-stage hybrid system in spectral domain to enhance the speech with additive noise. The pre-processor is developed for removing noise below hearing threshold. Spectral subtraction and wiener filter removes the background noises. Analysis is done on noisy speech signal database, which consists of speech signals corrupted by eight different real world noises at different SNR levels. The performance of the proposed algorithm is evaluated using different measures such as log-likelihood ratio, signal-to-noise ratio, mean square error and mean opinion score. Experiments results show the increase in the efficiency of the proposed enhancement algorithm.