Masked spectral components need no bits because they are inaudible

Evidence

Using some form of simultaneous masking model masking curves, which are different for tonal and nontonal sounds, a signal-to-masking ratio (SMR) is calculated and the bits allocated such that components that need a high SMR are given more bits than those that have a lower SMR. For components that have a negative SMR, no bits are allocated because these components are masked and therefore need not be transmitted. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2678

Categorization

• DEFINE: SMR (signal-to-masking ratio) is defined here as the criterion driving bit allocation.