Sub-band coders

• Exploit the frequency sensitivity of the auditory system
• Split the signal into sub-band using band pass filters, such as the example of figure 12
• Code each subband at an appropriate resolution - e.g. 4 bits per sample in the lower subbands and 2 bits per sample in the upper subbands
• Can also exploit auditory masking - use fewer bits if a neighboring subband is much louder
• Basis for the MPEG audio standard (5:1 compression of CD quality audio with no perceptual degradation)