OTTAWA, Quebec, Canada-Northern Telecom Ltd. announced its vocoder tests conducted at its Subjective Assessment Laboratory in Ottawa, Quebec, Canada, showed Code Division Multiple Access speech vocoders offer voice quality equivalent to wireline telephones.
The tests, carried out on behalf of the CDMA Development Group, were the first to include a formal subjective comparison of the performance of the leading speech codecs-8 kbps enhanced Variable Rate Codec and the Qualcomm 13 kbps Pure Voice Codec, said Nortel. Results also showed that the latest Time Division Multiple Access and Global System for Mobile communications coders are capable of providing wireline voice quality.
There were 120 listeners tested, said Nortel. The participants rated speech with input impairments such as background noise, as well as channel impairments to compare the voice quality CDMA with different coders.
