title: Effects of randomizing phase on the discrimination between amplitude-modulated and quasi-frequency-modulated tones.
abstract: This study investigated the bandwidth of phase sensitivity. Subjects discriminated amplitude-modulated tones (AM), and quasi-frequency-modulated tones (QFM) in a two-interval, forced-choice task. An adaptive threshold procedure was used to estimate the modulation depth needed to discriminate the stimuli as a function of carrier and modulation frequency. Non-monotonicities in threshold-bandwidth functions were often observed at higher modulation frequencies. The results are discussed in terms of two potential cues: (1) waveform envelope, (2) cubic distortion products. In order to degrade the information obtained from auditory distortions, the phase for the carrier frequency was randomly sampled from a uniform distribution, which diminished the non-monotonicities with minimal effect at lower modulation frequencies. Model simulations demonstrated that phase randomization degrades distortion product cues with only a modest effect on temporal cues. Final results show that maximum bandwidths for phase sensitivity (BW(max)) were not proportional to carrier frequencies.
authors.affiliation: Department of Cognitive Sciences, University of California, 2201 Social & Behavioral Sciences, Gateway Building, Irvine, CA 92697-5100, USA.
authors.forename: Hisaaki
authors.initials: H
authors.lastname: Tabuchi
authors.forename: Ewa
authors.initials: E
authors.lastname: Borucki
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Berg
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001299:Audiometry; D001306:Auditory Pathways / Q000502:physiology*; D001309:Auditory Threshold; D003463:Cues; D004192:Discrimination, Psychological; D006801:Humans; D008954:Models, Biological; D010897:Pitch Discrimination; D011571:Psychoacoustics; D011897:Random Allocation; D013997:Time Factors; D055815:Young Adult