title: Effect of amplitude modulation coherence for masked speech signals filtered into narrow bands.
abstract: Introduction of masker amplitude modulation (AM) can improve signal detection in a number of paradigms. In some cases this advantage depends on the coherence of modulation across a relatively wide frequency range. In the experiments described below, observers were asked to identify masked spondee words produced by a single male talker. The target spondees and masking noise were filtered into nine narrow bands, and the coherence of AM of either the speech signal or noise masker was manipulated. Inherent modulation of the masker bands was manipulated via assignment of real and imaginary values to the associated components of each band in the frequency domain, and AM of speech bands was achieved via multiplication with envelopes extracted from these maskers. Responses were based on two alternatives, four alternatives, or open response sets. The effect of masker AM coherence was highly dependent upon the size of the response set: coherent AM was associated with better thresholds in a two-alternative response set, but poorer thresholds in an open response set. Results with AM speech did not depend critically upon the across-frequency temporal synchrony of AM imposed on the speech material.
authors.affiliation: Department of Otolaryngology/Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA. ebuss@med.unc.edu
authors.forename: Emily
authors.initials: E
authors.lastname: Buss
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Wall
authors.forename: John H
authors.initials: JH
authors.lastname: Grose
mesh_terms: D000328:Adult; D001309:Auditory Threshold; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016011:Normal Distribution; D010470:Perceptual Masking; D013018:Sound Spectrography; D013061:Speech Acoustics; D013067:Speech Perception