Evaluation of ITU-T G.728 as a Voice over IP codec for Chinese Speech

Voice-over-IP is expected to become a popular service offered by the internet. Thus, it is important to ensure high quality of service. In this paper, we look at two standards proposed for evaluating the intelligibility of Chinese speech. Adopting the philosophy and methodology of the Diagnostic Rhyme Test (DRT) for testing English speech, the Chinese Diagnostic Rhyme Test (CDRT) evaluates the six elementary phonemic attributes of Chinese words. Since Chinese is a tonal language, an extension of CDRT called CDRT-Tone evaluates the tonal attributes of Chinese speech. These two tests were used to evaluate the ITU-T G.728 speech coder as a VoIP codec for Chinese speech. Results are compared to the previous evaluations on a GSM 06.10 coder.