A lossy audio compression algorithm is transparent if the original and decoded signal are indistinguishable to the human ear. The bit rate depends on the codec and the audio material. Some codecs (e.g. AAC, MP3) are optimized for transparent coding at a low data rate, others (e.g. VQF, MP3Pro, AAC+SBR, WMA) for distinguisable but pleasant reproduction at lower bit rates.

Typical data rates in kbps for different codecs are:

 MP1         288-320
 MP2         224-256
 MP3         160-224
 MPEG-2 AAC  128-160
 MPEG-4 AAC  112-144
 MPEGplus    160-200