Auditory Masking and the Critical Band

Abstract

Masked audiograms were studied as a function of the band-width, level, and frequency of a masking noise. In a reverse procedure, audiograms were determined when a movable, narrow, and approximately rectangular band of noise was used as a signal in the presence of one or more masking tones. In both cases changes in the masked audiograms as a function of band width made it possible to measure critical band width. When masked audiograms were studied as a function of level, discontinuous changes in their height and shape oc-curred when the masking stimulus reached a certain "transition" level. If masking noises of subcritical or critical width were used, the growth of masking with level contained a discontinuity at a level of the masking stimulus equal to about 50 db. An abrupt change in the shape of the masked audiograms occurred at the same level. The change of shape when a pure tone was the masking stimulus consisted in the appearance of a "notch" one critical band width above the frequency of the masking tone. Finds associated with band width parameter suggest interpretations of the critical band and of masking. The changes occurring at the transi-tion level may indicate the threshold of the inner hair cells.