Ah, that's a mistake, that should have read "introduced [quantization] noise", which reduces the SNR in A' vs A. If I understand you correctly, your discussion

Ah, that's a mistake, that should have read "introduced [quantization] noise", which reduces the SNR in A' vs A. If I understand you correctly, your discussion around intelligibility primarily applies to signal processing of voice vs general audio. Codecs such as MP3, AAC, etc. don't have the luxury of making assumptions about the signal content, and so aren't designed along those principles. E.g. speech codecs can generally run well at much lower bitrates than general audio codecs because they operate on a constrained domain of audio (i.e. speech). Regarding distortion management, see Rate-distortion optimization[1] for lossy audio codecs: where the purpose is to manage distortion within the limits of the bit rate supported by a communication channel or storage medium. [1] https://en.wikipedia.org/wiki/Quantization_(signal_processing)#Rate.E2.80.93distortion_optimization https://en.wikipedia.org/wiki/Quantization_(signal_processin...