Designing quantizers for peak levels wastes bits that masking could reclaim.

Evidence

Real signals often spend most of their time at low signal levels, but one has to design the quantizer to handle the maximum signal level, even if it isn’t used very often. This means that more bits are used than is strictly necessary most of the time. One way of reducing the number of bits needed to quantize an audio signal is to make the quantizer adapt to the level of the signal, because loud signals mask weaker signals, as discussed in Chapter 5. This type of quantizer is known as an “adaptive quantizer” and can save some bits. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2660

Categorization

• DEFINE: Introduces the adaptive quantizer and ties it directly to auditory masking as the bit-saving mechanism.