Evaluation of Methods for Approximating the Short-Time Energy Contour of Speech in Noise Based on Intelligibility Tests

The goal of the work described in this thesis is to determine the effect that adjusting the short-time engery [sic] contour of corrupted speech to match that of the uncorrupted speech has on the intelligibility of the resulting speech. While the effect that the short-time energy contour measured from the uncorrupted speech is of interest for comparisons sake, this signal is never available in any realistic situation, hence, a short-time energy contour estimate must be obtained in some way from the corrupted speech. To this end, various methods for estimating the short-time energy contour of speech signals in high levels of background noise are presented. These methods are evaluated on the basis of both subjective and objective measures. The objective measure consists of the mean-squared error comparison between the short-time energy contour estimated from the noisy signal and the short-time energy contour measured from the uncorrupted signal. The subjective measure consists of the Diagnostic Rhyme Test which is a test that is designed to measure the effects a processing scheme has on the intelligibility of the processed speech. Both measures are included since a high level of correlation between objective distance measures and subjective intelligibility scores has not been established in the literature. As an appendix to the thesis, a discussion of various modern spectral estimation techniques is presented with emphasis on the techniques used for identifying frequency components when the signal is embedded in high level noise