title: The dynamic range of useful temporal fine structure cues for speech in the presence of a competing talker.
abstract: Within an auditory channel, the speech waveform contains both temporal envelope (E(O)) and temporal fine structure (TFS) information. Vocoder processing extracts a modified version of the temporal envelope (E') within each channel and uses it to modulate a channel carrier. The resulting signal, E'(Carr), has reduced information content compared to the original "E(O) + TFS" signal. The dynamic range over which listeners make additional use of E(O) + TFS over E'(Carr) cues was investigated in a competing-speech task. The target-and-background mixture was processed using a 30-channel vocoder. In each channel, E(O) + TFS replaced E'(Carr) at either the peaks or the valleys of the signal. The replacement decision was based on comparing the short-term channel level to a parametrically varied "switching threshold," expressed relative to the long-term channel level. Intelligibility was measured as a function of switching threshold, carrier type, target-to-background ratio, and replacement method. Scores showed a dependence on all four parameters. Derived intensity-importance functions (IIFs) showed that E(O) + TFS information from 8-13 dB below to 10 dB above the channel long-term level was important. When E(O) + TFS information was added at the peaks, IIFs peaked around -2 dB, but when E(O) + TFS information was added at the valleys, the peaks lay around +1 dB.
authors.affiliation: Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge CB2 3EB, United Kingdom. mas19@cam.ac.uk
authors.forename: Michael A
authors.initials: MA
authors.lastname: Stone
authors.forename: Brian C J
authors.initials: BC
authors.lastname: Moore
authors.forename: Christian
authors.initials: C
authors.lastname: Füllgrabe
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001302:Audiometry, Speech; D001309:Auditory Threshold; D003463:Cues; D005260:Female; D006801:Humans; D008297:Male; D009622:Noise; D010470:Perceptual Masking; D013018:Sound Spectrography; D013061:Speech Acoustics; D013065:Speech Intelligibility; D013067:Speech Perception; D013997:Time Factors; D013998:Time Perception; D055815:Young Adult