Subjective evaluation of state-of-the-art two-channel audio codecs

The results of double-blind subjective tests are reported, which were conducted to examine the audio quality of several state-of-the-art two-channel audio codecs against a CD-quality reference. Implementations of the MPEG Layer 2, MPEG Layer 3, MPEG AAC, Dolby AC-3, and Lucent PAC codecs were evaluated at the Communications Research Centre in Ottawa, Canada, in accordance with the subjective testing procedures outlined in ITU-R Recommendation BS. 1116. The bit rates varied between 64 and 192 kbit/s per stereo pair. The study is unique in that this is the first time that these codecs have been compared in a single test. Clear results were obtained for comparing the subjective performance of the codecs at each bit rate. All codecs were software based and constituted the most current implementations at the time of testing. An additional hardware-based MPEG Layer 2 codec was included in the tests as a benchmark.