A MULTI-BAND SPECTRAL SUBTRACTION METHOD FOR SPEECH ENHANCEMENT
| Author: |
Kamath, Sunil Devdas |
| Advisor: |
Philip Loizou |
| URL: |
http://www.utdallas.edu/~loizou/thesis/sunil_ms_thesis.pdf
" target="_blank"> http://www.utdallas.edu/~loizou/thesis/sunil_ms_thesis.pdf
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| Completion Date: |
May 2001 |
| Degree: |
M.Sc./M.A. |
| Institution: |
University of Texas at Dallas |
| Abstract: |
The corruption of speech due to presence of additive background noise causes severe difficulties in various communication environments. This thesis addresses the problem of reduction of additive background noise in speech. The proposed approach is a frequency-dependent speech enhancement method based on the proven spectral subtraction method. Most implementations and variations of the basic spectral subtraction technique advocate subtraction of the noise spectrum estimate over the entire speech spectrum. However, real world noise is mostly colored and does not affect the speech signal uniformly over the entire spectrum. This thesis explores a Multi-Band Spectral Subtraction (MBSS) approach with suitable pre-processing of the speech data. Speech is processed into frequency bands and spectral subtraction is performed independently on each band using band-specific over-subtraction factors. This method provides a greater degree of flexibility and control on the noise subtraction levels that reduces artifacts in the enhanced speech, resulting in improved speech quality. The effect of the number of frequency band and the type of filter spacing (linear, logarithmic or mel) was investigated. Results showed that the proposed MBSS method with four linear-spaced frequency bands outperformed the conventional spectral subtraction method with respect to speech quality and reduced musical noise. |
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