Auditory Brainstem Responses to Sounds from Real and Virtual Locations

Presenter: JD Hairston

Faculty Sponsor: Lisa Sanders

School: UMass Amherst

Research Area: Psychology and Behavioral Sciences

Session: Poster Session 5, 3:15 PM - 4:00 PM, 163, C18

ABSTRACT

Auditory localization requires complex neural calculations.  That complexity is even greater in reverberant environments where sound, in addition to traveling directly from the source to the ears, also reflects off surfaces and reaches the ears from other directions a few milliseconds later.  Yet listeners can localize sound in reverberant environments and rely on auditory localization in many real-world circumstances.  For example, auditory localization is important for being able to understand one person talking in a room where many people are talking. The current study investigates subcortical responses to a speech sound under four spatial conditions.  In two of those conditions, a 40 ms /da/ syllable is presented from a loudspeaker in front of the participant or 70 degrees to the right of the participant (Free-Field conditions).  In the other two conditions, the syllable is presented from both the central and right loudspeaker, but with the sound starting from one location 4 ms before the other location (Precedence Effect conditions).  The Precedence Effect describes the fact that listeners localize a sound presented from multiple locations based mostly on the lead location.  By recording Auditory Brainstem Responses (ABRs) to thousands of repetitions of the syllable in each condition, we were able to identify differences in early auditory processing of Free-Field and Precedence Effect localization.  These results contribute to an understanding of neural mechanisms involved in real-world sound localization, and suggest intervention directions for listeners who struggle to understand speech in noisy conditions.


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