The plausibility hypothesis

The plausibility hypothesis was originally introduced to explain human sound localization behavior in situations with a single sound-reflecting surface capable of producing abnormally large interaural time cues. The hypothesis states that “interaural time cues are weighted by listeners according to their plausibility” and that “listeners assess plausibility as though all sounds are direct” [Rakerd and Hartmann, J. Acoust. Soc. Am. 78, 524–533 (1985)]. Thus, the hypothesis explained why interaural time cues contributed to perceived source direction in certain situations but not in other situations with implausible cue values. A key aspect of the plausibility hypothesis is its acknowledgment of the role of expectation in governing perception. Against a backdrop of contemporary auditory research that emphasized the role of stimulus-driven bottom-up processing, appeal to the top-down aspects of expectation was groundbreaking. Hartmann and Rakerd went on to successfully apply the plausibility hypothesis to other aspects of binaural and spatial hearing, such as understanding the Franssen Illusion. Here we discuss additional high-level auditory phenomena, including distance perception and perceptual de-reverberation, through the lens of the plausibility hypothesis.