The rapid decline in interaural-time-difference sensitivity for pure tones is explained by a single frequency-channel model
Update: 2023-08-04
Description
Link to bioRxiv paper:
http://biorxiv.org/cgi/content/short/2023.08.04.551950v1?rss=1
Authors: Goupell, M. J., Stecker, G. C., Williams, B. T., Bilokon, A., Tollin, D. J.
Abstract:
The interaural time difference (ITD) is a primary horizontal-plane sound localization cue computed in the auditory brainstem. ITDs are accessible in the temporal fine structure of pure tones with a frequency of no higher than about 1400 Hz. Explaining how listeners' ITD sensitivity transitions from very best sensitivity near 700 Hz to impossible to detect within 1 octave currently lacks a clear physiological explanation. Here, it was hypothesized that the rapid decline in ITD sensitivity is dictated not to a central neural limitation but by initial peripheral sound encoding, specifically, the low-frequency edge of the cochlear excitation pattern produced by a pure tone. To test this hypothesis, ITD sensitivity was measured in 16 normal-hearing listeners as a joint function of frequency (900-1500 Hz) and level (10-50 dB sensation level). Performance decreased with increasing frequency and decreasing sound level. The slope of performance decline was 90 dB/octave, consistent with the low-frequency slope of the cochlear excitation pattern. Consequently, fine-structure ITD sensitivity near 1400 Hz may be conveyed primarily by "off-frequency" activation of neurons tuned to lower frequencies near 700 Hz. Physiologically, this could be realized by a single narrow channel near 700 Hz that conveys fine-structure ITDs. Such a model is a major simplification and departure from the classic formulation of the binaural display, which consists of a matrix of neurons tuned to a wide range of relevant frequencies and ITDs.
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http://biorxiv.org/cgi/content/short/2023.08.04.551950v1?rss=1
Authors: Goupell, M. J., Stecker, G. C., Williams, B. T., Bilokon, A., Tollin, D. J.
Abstract:
The interaural time difference (ITD) is a primary horizontal-plane sound localization cue computed in the auditory brainstem. ITDs are accessible in the temporal fine structure of pure tones with a frequency of no higher than about 1400 Hz. Explaining how listeners' ITD sensitivity transitions from very best sensitivity near 700 Hz to impossible to detect within 1 octave currently lacks a clear physiological explanation. Here, it was hypothesized that the rapid decline in ITD sensitivity is dictated not to a central neural limitation but by initial peripheral sound encoding, specifically, the low-frequency edge of the cochlear excitation pattern produced by a pure tone. To test this hypothesis, ITD sensitivity was measured in 16 normal-hearing listeners as a joint function of frequency (900-1500 Hz) and level (10-50 dB sensation level). Performance decreased with increasing frequency and decreasing sound level. The slope of performance decline was 90 dB/octave, consistent with the low-frequency slope of the cochlear excitation pattern. Consequently, fine-structure ITD sensitivity near 1400 Hz may be conveyed primarily by "off-frequency" activation of neurons tuned to lower frequencies near 700 Hz. Physiologically, this could be realized by a single narrow channel near 700 Hz that conveys fine-structure ITDs. Such a model is a major simplification and departure from the classic formulation of the binaural display, which consists of a matrix of neurons tuned to a wide range of relevant frequencies and ITDs.
Copy rights belong to original authors. Visit the link for more info
Podcast created by Paper Player, LLC
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