Adaptation of the relative onset time of two-component tones

Abstract

The results of three selective adaptation experiments employing nonspeech signals that differed in temporal onset are reported. In one experiment, adaptation effects were observed when both the adapting and test stimuli were selected from the same nonspeech test continuum. This result was interpreted as evidence for selective processing of temporal order information in nonspeech signals. Two additional experiments tested for the presence of cross-series adaptation effects from speech to nonspeech and then from nonspeech to speech. Both experiments failed to show any evidence of cross-series adaptation effects, implying a possible dissociation between perceptual classes of speech and nonspeech signals in processing temporal order information Despite the absence of cross-series effects, it is argued that the ability of the auditory system to process temporal order information may still provide a possible basis for explaining the perception of voicing in stops that differ in VOT. The results of the present experiments, taken together with earlier findings on the perception of temporal onset in nonspeech signals, were viewed as an example of the way spoken language has exploited the basic sensory capabilities of the auditory system to signal phonetic differences.

Figure 1

Schematic representations of three stimuli differing in relative onset time: leading (−50 msec), simultaneous (0 msec), and lagging (+50 msec).

Figure 2

Average nanspeech (TOT) identification functions for baseline and after adaptation in Experiment 1. The −50-msec nonspcech TOT adaptor group is shown on the left; the +50-msec nonspeech TOT adaptor group is shown on the right.

Figure 3

Average nonspeech (TOT) identification fonctions for baseline and after adaptation in Experiment 2. The −50-msec VOT speech adaptor group is shown on the left; the +50 msec VOT speech adaptor group is shown on the right.

Figure 4

Average speech (VOT) identification functions for baseline and after adaptation in Experiment 3. The −50-msec nonspcech TOT adaptor group is shown on the left; the +50-msec TOT adaptor group is shown on the right.