Complex sounds and critical bands.
Bertram Scharf · Psychological Bulletin · 1961
Studies of the responses of human observers to bands of noise and other complex sounds have led to the meas-ure of what appears to be a basic unit of hearing, the critical band. When the frequency spectrum of a stimu-lating sound is narrower than the critical band, the ear reacts one way; when the spectrum is wider, it reacts another way. For example, experi-ments show that at values less than the critical bandwidth, both loud-ness and absolute threshold are in-dependent of bandwidth; only when the critical bandwidth is exceeded do the loudness and the absolute threshold increase with the width