UBC Theses and Dissertations

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UBC Theses and Dissertations

Real-time implementation and evaluation of an adaptive silence deletion algorithm for speech compression Rose, Christopher


The removal of nonessential acoustic material or silence from speech can significantly reduce the average bit rate required for speech coding. Silence deletion can be used to reduce the channel capacity required for speech transmission, or to reduce the storage requirements for voice mail applications. This thesis describes the real-time implementation of a silence compression algorithm using a TMS320C25 digital signal processor. Substantial modifications were made to an earlier silence detection algorithm to enable its implementation in real time, as well as to improve the performance of the algorithm in a variety of speech environments. Up to 50% compression on single speaker speech is possible with our silence compression algorithm without significant loss of playback signal quality. The silence compression algorithm was implemented in a way that enabled source coding techniques to be used to further compress the speech portions of the acoustic signal. The use of 4-bit ADPCM to code the speech resulted in an average bit rate below 19.2 kbit/s.

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