الفهرس 
Bit Rate Reduction MethodsOnly 14 pages are availabe for public view
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Abstract
Recent years have witnessed significant progress in the compression of
speech. This has been the result of an inter working of coding theory and
signal processing. Advances in compression have been accompanied by
numerous standards for digital encoding and communication. The generic
problem in signal compression is to minimize the bit rate in the digital
representation of signal. while maintaining required levels of signal quality.
This thesis consist of two parts, the first part is devoted to study of a
multitude speech coding methods from point of view of time and spectral
waveform, and study the bit rate compression against the speech quality and
coding delay for each of them. We put in mind the complexity of each
method.
In the second part of this thesis, the study of new generation of bit
reduction method which is called code excitation linear prediction CELP
coder, we implemented the coder with bit rate 4.8 kb/s by using and testing
the prediction technique. and codebook design. A low delay version of the
coder called lattice 10\\· delay CELP was tested and implemented. Also, a
modification in the coder design to reduce the computation complexity is
proposed in this thesis. Performance comparison between these two different
cases was carried out and evaluated objectively and subjectively by using
real speech signal.