critical band
the band of frequencies in a masking noise that are effective in masking a tone of a given frequency (see auditory masking). The width of this band, in hertz (Hz), is the critical bandwidth. For example, in detecting a 1 kHz tone in white noise, only frequency components in the noise between 920 Hz and 1080 Hz contribute significantly to the masking: The critical band is from 920 Hz to 1080 Hz, and the critical bandwidth is 160 Hz. In psychoacoustics there are many manifestations of critical-band “filtering,” including spectral effects in loudness summation and monaural phase effects. See also auditory filter; frequency selectivity. [first described in 1940 by U.S. physicist Harvey Fletcher (1884–1981)]