In the wireless communication system, IS-96 is one of the speech coding algorithms which provide good quality at low bit rate. Under the noisy environment, although the error protection and error concealment of IS-96 have noticeable improvements on speech quality, the error in the frame can still cause performance degradation. In this thesis, we use selective error concealment method in which the error concealment is only applied when the error rate is relatively high. From the analysis of channel error rate, a simple rule based on the BCH code to classify the channel error rate is exploited. In simulation results, the quality of synthesized speech is improved at a wide range of channel error rates.

In addition, we implement a real-time audio decoder under Unix on sparc20 workstation. By utilizing the function calls, fork and pipe, the decoding and display functions can be performed simultaneously.