Low bit rate speech coding for single speakers

Speech coding is still a popular area for research and has received much interest over the past two decades. The thirst for low bit rate speech coding algorithms continues, fueled by the ever increasing number of subscribers to the mobile/domestic communication networks. This has biased the research conducted for speech coding towards this type of application, leaving less useful (or profitable?) applications in the background. Until the mid-eighties good quality synthesized speech at low bit rates eluded the speech coding fraternity. Even from the early days of speech coding, concentration on producing speech coders which could perform well when coding a variety of different speakers had been the main concern-little attention had been paid to a coder which could code just a single voice. The applications where such a coder could be employed are limited, but this does not mean that they are unimportant. This paper acts as an introduction to speaker dependent coders highlighting their associated problems. Possible techniques which may be used to accomplish single speaker coding are outlined and applications are described