Mechanisms Mediating the Perception of Complex Acoustic Patterns

Abstract

Abstract : Three studies dealing with perception of acoustic repetition for long-duration complex sounds have been completed. 1) Repetition of 'frozen' Gaussian noise can be detected for infratonal repetition frequencies from 1 Hz through 20 Hz (repetition frequencies above 20 Hz are tonal). Infratonal repetition might be perceived either through the detection of the reoccurrence of singularities within the acoustic pattern, or through a holistic recognition of the entire pattern. This investigation indicated that a holistic recognition of the complex sound is normally responsible for detection of periodicity. 2) Illusory continuity of interrupted tones (pulsation thresholds) have been used to study peripheral auditory mechanisms. The investigators found that illusory continuity also occurs in the infratonal range, requiring revision of the theories of basilar membrane mechanics based on the pulsation threshold paradigm. 3) The investigators demonstrated that 'frozen' noises repeated at infratonal frequencies at one ear (silence at the other ear) are detected by some listeners with much greater clarity than when the other ear receives the signal. Ear advantages of this nature have not been observed with other types of complex sounds, and this finding has some interesting implications for auditory theory. Keywords: Auditory perception; Infrasonic radiation.