What is the Signal-To-Noise Ratio (SNR) of MPEG Audio?
For a perceptual codec, this is not really a relevant question. The SNR is a very bad measure of perceptual audio quality, even for a waveform coder. The SNR measured in a conventional way, may vary from a few dB up to more than 100 dB, mostly depending on the signal, while no noise is audible in any of these cases. Within the International Telecommunication Union (ITU-R), a task group (TG 10/4) is working on the development of a more appropriate objective measurement system, based on perceptual models. For the moment, one has to rely on the human ear as a measuring instrument, i.e. there are no other reliable means to determine the quality of a perceptual codec than listening tests. Even when a standardised perceptually based objective measurement system is available, listening tests will still be wise for comparison of different audio codecs. On the basis of psychoacoustics, it must be noted that within the range of 5 to 80 dB SNR, it is easily possible to generate two test signals,
