Review of AMR speech codec-and distributed speech recognition-based speech-enabled services

In this paper, we investigate the usefulness of general-purpose speech codecs and dedicated speech recognition codecs for speech-enabled services. Specifically, we focus on 3rd generation WCDMA systems using the adaptive multi-rate (AMR) speech codec, in comparison with the distributed speech recognition (DSR) framework. Speech recognition experiments are carried out with the AMR speech codec in a simulated packet-switched network. The performance of the DSR codec is assumed to be unaffected by transmission errors. Experimental results in British English and Mandarin Chinese indicate that no significant performance difference can be observed between the AMRand DSR-based recognition systems. The gain from using the dedicated DSR codec is unlikely to provide a perceptible improvement in terms of quality of service for the end-users. In the light of the experimental results achieved, and other implementation and economical issues, it is concluded that the use of dedicated speech recognition codecs, such as DSR, does not offer tangible benefits in real-world systems and services.