Real audio signals cluster toward small amplitudes, not the uniform statistics quantizers assume.

Evidence

Adaptive quantizers attempt to make the input signal statistics match the ideal uniform distribution for maximum signal to noise. However, even with fine-scale steps, this is rarely achieved, and there is still a tendency for the small signal levels to be more probable. Furthermore, the higher levels may have a better signal-tonoise ratio than is strictly necessary for masking. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2663

Categorization

• XREF: Connects to Chapter 2’s threshold-of-hearing discussion and the masking principles introduced earlier, which this chapter combines.