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Adaptation in the processing of interaural time differences revealed by the auditory localization aftereffect
1Information Science Research Laboratory, NTT Basic Research Laboratories, Kanagawa, Japan. kashino@av-hp.brl.ntt.co.jp
The Journal of the Acoustical Society of America
|June 24, 1998
Summary
The auditory localization aftereffect shifts sound perception based on prior exposure. This effect is strongest with similar frequencies and interaural time differences (ITDs), suggesting gain changes in specific neural units.
Area of Science:
- Auditory perception
- Psychoacoustics
- Neuroscience
Background:
- The auditory localization aftereffect demonstrates how recent auditory exposure influences sound localization.
- This phenomenon involves a perceptual shift away from an adapting sound's interaural time difference (ITD).
Purpose of the Study:
- To investigate the frequency and ITD selectivity of the auditory localization aftereffect.
- To model the underlying neural mechanisms responsible for this aftereffect.
Main Methods:
- Two experiments were conducted using sinusoidal tones presented via headphones.
- Experiment 1 examined frequency selectivity using the method of constant stimuli.
- Experiment 2 assessed ITD selectivity by measuring perceived azimuth shifts.
Main Results:
- The aftereffect magnitude was maximal for similar adapter and test frequencies, diminishing with larger frequency differences.
- The largest aftereffect occurred when adapter and test ITDs differed by approximately 250 microseconds.
- Results were successfully simulated by an interaural cross-correlation model with gain control.
Conclusions:
- The auditory localization aftereffect exhibits selectivity for both frequency and ITD.
- Findings support a model where gain of ITD-selective neural units is modulated by recent auditory input.
- This modulation occurs after binaural interaction but before across-frequency integration.