Abstract
The auditory system uses interaural time and level differences (ITD and ILD) as cues to localize and lateralize sounds. The availability of ITDs and ILDs in the auditory system is limited by neural phase-locking and by the head size, respectively. Although the frequency-specific limitations are well known, the relative contribution of ITDs and ILDs in individual frequency bands in broadband stimuli is unknown. To determine these relative contributions, or spectral weights, listeners were asked to lateralize stimuli consisting of eleven simultaneously presented 1-ERB-wide noise bands centered between 442 and 5544 Hz and separated by 1-ERB-wide gaps. Either ITDs or ILDs were varied independently across each noise band, while fixing the other interaural disparity to either 0 dB or 0 μs. The weights were obtained using a multiple linear regression analysis. In a second experiment, the effect of auditory enhancement on the spectral weights was investigated. The enhancement of single noise bands was realized by presenting ten of the noise bands as preceding and following sounds (pre- and post-cursors, respectively). Listeners were asked to lateralize the stimuli as in the first experiment. Results show that in the absence of pre- and post-cursors, only the lowest or highest frequency band received highest weight for ITD and ILD, respectively. Auditory enhancement led to significantly enhanced weights given to the band without the pre- and post-cursor. The weight enhancement could only be observed at low frequencies, when determined with ITD cues and for low and high frequencies for ILDs. Hence, the auditory system seems to be able to change the spectral weighting of binaural information depending on the information content.
Highlights
An important ability of the auditory system is spatial hearing
The statistical values of the comparisons across the frequency bands are shown in Tables 1 and 2 for the spectral weights of ITDs and ILDs, respectively. p values in the Tables with a value ≤ 0.05 are indicated in italics
No other significant differences were found for the spectral weights of ILDs when comparing across frequency bands
Summary
An important ability of the auditory system is spatial hearing. This ability enables the localization of sound sources in auditory space (see Middlebrooks and Green 1991, for a review) and to improve the understanding of speech in environments with interfering sound sources (e.g., Bronkhorst 2000). The complete set of cues underlying spatial hearing can be derived from the head-related transfer functions of the two ears relative to the location of the sound source Two of these cues are interaural disparities in time (interaural time difference, ITD) and interaural disparities in level (interaural level difference, ILD). The spectral dominance of ITD and ILD is AHRENS ET AL.: Weighting of binaural lateralization cues commonly referred to as the Duplex theory and are widely acknowledged in the literature (e.g., Macpherson and Middlebrooks 2002) It is, less clear what the contribution of the different cues in the different frequency bands is in more realistic conditions with broadband stimuli
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Journal of the Association for Research in Otolaryngology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
