title: Gap duration discrimination for frequency-asymmetric gap markers: psychophysical and electrophysiological findings.
abstract: This study investigated gap duration discrimination (GDD) for frequency-asymmetric gap markers, where one marker was a two-tone complex consisting of a primary tone and a secondary tone, and the other marker was the primary tone alone. Three experiments were undertaken to examine the order effect wherein performance is better when the two-tone marker is the leading marker than when it is the trailing marker. Experiment 1 demonstrated that GDD for frequency-asymmetric markers is intermediate between the boundaries of within-frequency-channel versus across-frequency-channel processing. Experiment 2 compared psychophysical performance with auditory brainstem responses (ABRs) elicited by the same stimuli. Whereas GDD thresholds were elevated for a complex trailing marker relative to a within-frequency-channel baseline, ABRs elicited by the complex marker were more robust. Experiment 3 tested the hypothesis that poor GDD performance with frequency-asymmetric markers is due to some form of nonenergetic, or informational, masking. The results did not support a role for informational masking conferred by synthetic listening; however, informational masking conferred by the occurrence of novel spectral events provided a parsimonious account. One possible interpretation is that the capacity to accurately encode a gap is undermined by the occurrence of novel spectral events that engage limited attentional resources.
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7070, USA. jhg@med.unc.edu
authors.forename: John H
authors.initials: JH
authors.lastname: Grose
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Hall
authors.forename: Emily
authors.initials: E
authors.lastname: Buss
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D001309:Auditory Threshold; D016057:Evoked Potentials, Auditory, Brain Stem; D006801:Humans; D008875:Middle Aged; D046709:Pattern Recognition, Physiological; D010470:Perceptual Masking; D012016:Reference Values; D015203:Reproducibility of Results; D017603:Signal Detection, Psychological; D013998:Time Perception / Q000502:physiology*