Temporal and spectral basis of the features perceived in repeated noise.

When a half-second segment of a noise is played repeatedly, it initially creates a "whooshing" perception. With longer listening, however, individual features like "clanks" and "rasping" emerge. It is easy to tap the period of the perceived structure. This offers a possibility to investigate the mechanisms underlying the perception of these distinct features. The present study addresses the subject of the temporal and spectral extent of the physical correlates of these percepts. Five subjects participated in this study, and their tapping is in notable, although not perfect correlation. The physical correlate of the features can be confined in time to intervals as small as 100 ms. This segment of the stimulus is processed largely independently from the rest of the noise sample. Spectral processing is, in general, local. Some features, however, are spread over more than one octave. In 3 cases out of 25, across-channel processing is apparent.