Modulation rate discrimination for unresolved components: temporal cues related to fine structure and envelope.
The present study investigated the hypothesis that the cues for modulation rate discrimination for unresolved spectral components differ as a function of the spectral region occupied by the stimuli. Specifically, it was hypothesized that when components occupy relatively low spectral regions, phase locking both to the fine structure and to the envelope are useful cues. However, as the spectral region occupied by the components increases, phase locking to the fine structure becomes less robust, whereas phase locking to the envelope remains as a potentially strong cue. Observers were asked to detect a decrease in modulation rate for carrier frequencies between 1500 and 6000 Hz. Both amplitude-modulated (AM) and quasifrequency-modulated (QFM) tones were used in order to produce stimuli having strong and weak envelope cues, respectively. Although there were marked individual differences, the results showed an interaction between modulation type and spectral region, with AM and QFM performance being relatively similar at low spectral region, but with QFM showing a steeper reduction in performance as the spectral region of the carrier frequency increased. Overall, the data are consistent with an interpretation that pitch perception for unresolved components depends upon both fine structure and envelope cues, and that the relative importance of these cues depends upon the spectral region occupied by the stimuli.
Hall
Joseph W
JW
Department of Otolaryngology Head and Neck Surgery, University of North Carolina Medical School, 610 Burnett-Womack Building, Campus Box 7070, Chapel Hill, North Carolina 27599-7070, USA. jwh@med.unc.edu
Buss
Emily
E
Grose
John H
JH
D000328:Adult; D001288:Attention; D005260:Female; D006801:Humans; D008297:Male; D010897:Pitch Discrimination; D011571:Psychoacoustics; D013018:Sound Spectrography; D013998:Time Perception