QUALITY EVALUATION OF LPC BASED LOW BIT RATE SPEECH CODERS

Significant improvements are being reported these days in the coding of speech signals “with high quality at low bit rates. The need for low-bitrate speech coding algorithms continues, supported by the ever-increasing number of users” in wireless communication networks. Linear Prediction coders form important class speech coders with low bitrates. This paper describes the software level simulation and performance evaluation of CELP (4.8Kbps), LD-CELP (16 Kbps), MELP (2.4 Kbps), and CS-ACELP (8Kbps, 6.4 Kbps) speech coders. Even though all e coder outputs match with the input signal, the results from the error resilience test and MOS score show that the output quality of CS-ACELP is much better than the other three coders. The CS-ACELP coder performed well both in a quiet environment and in a noisy environment at a bit rate of 6.4Kbps.