Gap duration discrimination for frequency-asymmetric gap markers: Psychophysical and electrophysiological findings
GDD thresholds for individual observers (open symbols) and group mean (solid symbol) for the 4 conditions of experiment 1. Error bars are standard deviation.
GDD thresholds for individual observers (open symbols) and group mean (solid symbol) for the 2 conditions of experiment 2. Error bars are standard deviation.
Upper schematics illustrate the position of the trigger pulse relative to the onset ramp (left) and the offset ramp (right). The stimulus, duration is for illustration purposes only. Lower panels show ABR waveforms from three observers elicited by stimulus onset (left pair of panels) and stimulus offset (right pair of panels). For each observer, the overlaid traces in the left-hand panel are individual sweeps, and the single trace in the right-hand panel is the weighted average of the individual sweeps. The arrows mark the position of wave .
ABR waveforms from one individual. The left column shows individual traces overlaid and the right column shows weighted averages. The upper row shows the reference condition where the leading marker was removed and only the primary tone trailing marker was present. The center block of rows shows the responses for the baseline within-frequency-channel condition set where the leading and trailing markers consisted of the primary tone alone. Each row depicts a fixed gap duration as stipulated in the inset. The bottom block of rows shows responses for the frequency-asymmetric condition set. The vertical line in the right column is positioned at the wave latency for the reference condition.
Weighted average ABR traces from six observers. The upper row denotes the reference condition with no forward masking, with the dashed line indicating the latency of wave . The center block of traces are elicited by the isofrequency markers with fixed gap durations as indicated in the left column. The lower block of traces are elicited by frequency-asymmetric markers at two fixed gap durations.
Wave latency shift (upper panel) and amplitude change (lower pannel) from baseline as a function of gap duration. Filled symbols connected by lines are individual data for the isofrequency condition set. The thick solid line indicates the group mean. Unfilled symbols are individual data for the frequency-asymmetric condition set. The dashed line indicates the group mean.
GDD thresholds for test 1 of experiment 3. For each mode of presentation (monaural, dichotic, diotic), individual data for the two-tone leading marker and the two-tone trailing marker are shown as connected open symbols. The solid circles are mean data, with standard deviation error bars.
GDD thresholds for test 2 of experiment 3. The left panel shows baseline isofrequency thresholds. The center panel shows thresholds for the frequency-asymmetric marker pair where the secondary tones were pure tones. The right panel shows thresholds for the frequency-asymmetric marker pair where the secondary tones were FM tones. In each panel, individual data for the three-tone leading marker and the three-tone trailing marker are shown as connected open symbols. The solid circles are mean data, with standard deviation error bars.
GDD thresholds for a standard gap duration of . The left panel shows baseline isofrequency thresholds. The right panel shows thresholds for the frequency-asymmetric markers plotted as a function of the number of tones in the leading and trailing markers. Solid circles are mean data; standard deviation, and individual data are shown as open symbols.
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