Detection of silent intervals between noises activating different perceptual channels: Some properties of “central” auditory gap detection

Abstract

This article describes four experiments on gap detection by normal listeners, with the general goal being to examine the consequences of using noises in different perceptual channels to delimit a silent temporal gap to be detected. In experiment 1, subjects were presented with pairs of narrow-band noise sequences. The leading element in each pair had a center frequency of 2 kHz and the trailing element's center frequency was parametrically varied. Gap detection thresholds became increasingly poor, sometimes by up to an order of magnitude, as the spectral disparity was increased between the noise bursts that marked the gap. These data suggested that gap-detection performance is impoverished when the underlying perceptual timing operation requires a comparison of activity in different perceptual channels rather than a discontinuity detection within a given channel. In experiment 2, we assessed the effect of leading-element duration in within-channel and between-channel gap detection tasks. Gap detection thresholds rose when the duration of the leading element was less than about 30 ms, but only in the between-channel case. In experiment 3, the gap-detection stimulus was redesigned so that we could probe the perceptual mechanisms that might be involved in stop consonant discrimination. The leading element was a wideband noise burst, and the trailing element was a 300-ms bandpassed noise centered on 1.0 kHz. The independent variable was the duration of the leading element, and the dependent variable was the smallest detectable gap between the elements. When the leading element was short in duration (5-10 ms), gap thresholds were close to 30 ms, which is close to the voice onset time that parses some voiced from unvoiced stop consonants. In experiment 4, the generality of the leading-element duration effect in between-channel gap detection was examined. Spectrally identical noises defining the leading and trailing edges of the gap were presented to the same or to different ears. There was a leading-element duration effect only for the between channel case. The mean gap threshold was again close to 30 ms for short leading-element durations. Taken together, the data suggest that gap detection requiring a temporal correlation of activity in different perceptual channels is a fundamentally different task to the discontinuity detection used to execute gap detection performance in the traditional, within-channel paradigm.

Learning strategy determines auditory cortical plasticity

“…Acoustic onsets are known to have a privileged status with respect both to perception and to auditory cortical discharge (Phillips & Heining, 2002). They are especially important in speech perception for phonetic identification (Phillips, Taylor, Hall, Carr, & Mossop, 1997) and even in music perception for identification of timbre and the type of instrument producing sound (Saldanha & Corso, 1964). Timbre is a biologically significant feature of natural sounds.…”

Cortical Evoked Response to Gaps in Noise: Within-Channel and Across-Channel Conditions

“…GDTs were obtained monotically from the right ear using stimuli and methods identical to those used previously in our laboratory (e.g., Lister & Roberts, 2005;Lister, et al, 2002) and similar to those used by others (e.g., Phillips, et al, 1997). There were two stages in obtaining behavioral GDTs.…”

“…When the noise bands that mark the gap are of different frequencies, known as across-channel gap detection, the task is more difficult and GDTs are larger (Lister & Roberts, 2005;Lister, et al, 2002). Because the phonemes that precede and follow temporal cues in speech are never identical, across-channel gap detection is thought to be more representative of the temporal cues important for speech perception than within-channel gap detection (Formby, Gerber, Sherlock, & Magder, 1998;Phillips, Taylor, Hall, Carr, & Mossop, 1997); therefore, this condition has received great interest in recent years.It has been suggested that detection of gaps between markers that are close (or overlap) in frequency is relatively easy because it requires monitoring activity in a single neural channel. For gaps between markers that differ in frequency, the listener must make a decision regarding the relative timing between the offset of neural activity in one channel and the onset in an entirely different channel (Formby, et al, 1998;Grose, Hall, Buss, & Hatch, 2001).…”

“…When the noise bands that mark the gap are of different frequencies, known as across-channel gap detection, the task is more difficult and GDTs are larger (Lister & Roberts, 2005;Lister, et al, 2002). Because the phonemes that precede and follow temporal cues in speech are never identical, across-channel gap detection is thought to be more representative of the temporal cues important for speech perception than within-channel gap detection (Formby, Gerber, Sherlock, & Magder, 1998;Phillips, Taylor, Hall, Carr, & Mossop, 1997); therefore, this condition has received great interest in recent years.…”

Estudo da vantagem da orelha direita em teste de detecção de gap

“…[1][2][3][4][5][6][7] The auditory ability for temporal resolution is the minimum time required for separating or resolving acoustic events. 8,9 In trying to locate the physiological mechanism of temporal resolution, some authors have suggested that auditory nerve fibers participate significantly in the process.…”