Year

1998

Degree Name

Master of Engineering (Hons.)

Department

School of Electrical, Computer and Telecommunications Engineering

Abstract

This thesis deals with waveform interpolation speech coding. Speech coding in the last decade has been dominated by the CELP paradigm. CELP algorithms offer highquality speech compression at bit rates from 4 to 16 kb/s. Recent research efforts have been oriented to a new generation of speech coding algorithms operating at bit rates of 2.4kb/s and below. CELP and its derivative architectures appear to be inadequate to meet the increasing quality objective. This is due to the small bit budget to adequately represent the original signal. A major source of distortion in CELP is an inaccurate degree of periodicity of the speech signal. The Waveform interpolation (WI) algorithm is intended to preserve natural periodicity by representing speech as an evolving set of pitch cycle waveforms (known as the prototype waveform or Characteristic Waveform). The waveform interpolation (WI) paradigm was found to provide state-of-the-art performance at 2.4kb/s.

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