http://www.aes.org/e-lib/browse.cfm?elib=18523 :

The Effects of MP3 Compression on Perceived Emotional Characteristics in Musical Instruments

(...) Instrument sounds were compressed with three different bit rates. As a preliminary step, we listened to the sounds compressed at different bit rates and judged that 112 Kbps sounds were the lowest bit rate that sounded nearly indistinguishable from the original sounds. Sounds at 32 Kbps had obvious artifacts. We selected 56 Kbps as an intermediate bit rate, representing medium quality between indistinguishable and obvious artifacts (i.e., some artifacts). Though these particular bit rates may not be as common in practice, they are representative of the basic levels of compression.

Hmm... comment dire...

C'est triste de voir l'AES publier ce genre de trucs, ils sont plutôt sérieux d'habitude...