Adjustment of interaural-time-difference analysis to sound level

Sieveke, Ida; Leibold, Christian ; Kaiser, Katharina; Grothe, Benedikt and Wiegrebe, Lutz (2010): Adjustment of interaural-time-difference analysis to sound level. In: Lopez-Poveda, Enrique A. (ed.) : (2010): The neurophysiological bases of auditory perception : [contains the papers presented at the 15th International Symposium on Hearing (ISH) ..., held ..., Santa Marta de Tormes, Salamanca, Spain, between 1st and 5th June 2009]. New York: Springer. pp. 325-336

Abstract

To localize low-frequency sound sources in azimuth, the binaural system compares the timing of sound waves at the two ears with microsecond precision. A similarly high precision is also seen in the binaural processing of the envelopes of high-frequency complex sounds. Both for low- and high-frequency sounds, interaural time difference (ITD) acuity is to a large extent independent of sound level. The mechanisms underlying this level-invariant extraction of ITDs by the binaural system are, however, only poorly understood. We use high-frequency pip trains with asymmetric and dichotic pip envelopes in a combined psychophysical, electrophysiological, and modeling approach. Although the dichotic envelopes cannot be physically matched in terms of ITD, the match produced perceptually by humans is very reliable, and it depends systematically on the overall sound level. These data are reflected in neural responses from the gerbil lateral superior olive and lateral lemniscus. The results are predicted in an existing temporal-integration model extended with a level-dependent threshold criterion. These data provide a very sensitive quantification of how the peripheral temporal code is conditioned for binaural analysis.

• Item Type: Book Section
• Keywords: Binaural hearing; loudness; envelope; spike timing
• Faculties: Biology > Department Biology II > Neurobiology
• Subjects: 500 Science > 570 Life sciences; biology
• ISBN: 978-1-4419-5685-9 ; 1-4419-5685-9
• Place of Publication: New York
• Language: English