A STUDY OF CELP SPEECH CODERS

Abstract

Speech coding has been an ongoing area of research for several decades.Although with the emergence of optical fibers, bandwidth in wired communications has become inexpensive, there is a growing need for speech bandwidth compression in wireless cellular and satellite communications. In particular, cellular communication has been enjoying tremendous. growth and there is a great deal of R&D activity geared towards establishing global portable communications through, wireless personal communication networks (PCN's). In the context of multimedia communications, there is a trend toward integrating voice relateed applications(e.g.,voice mail) on desktop and portable personal computers. Speech coding, the efficient representation of speech in digital form is one of the key technologies in most of these applications. Speech coding involves sampling and amplitude quantization. The objective of speech coding is to represent speech with a minimum number of bits while maintaining its perceptual quality. The quantization can be direct or parametric.Direct quantization implies binary representation of the speech samples themselves while parametric quantization involves binary representation of speech model or speech parameters....