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Infant Auditory Processing and Event-related Brain Oscillations
Published on: July 1, 2015
Frequency-following response: effects of interaural time and intensity differences.
B B Ballachanda1, G Moushegian
1Department of Speech and Hearing Sciences, University of New Mexico, Albuquerque 87131, USA.
Journal of the American Academy of Audiology
|March 31, 2000
Summary
The frequency-following response (FFR) can reveal how the brainstem processes sound localization cues like interaural time differences (ITDs). This research shows FFRs distinguish between different ITDs, suggesting potential for assessing binaural hearing.
Area of Science:
- Neuroscience
- Auditory Neuroscience
- Bioacoustics
Background:
- Sound localization in mammals relies on brainstem mechanisms.
- The frequency-following response (FFR) reflects neural activity synchronized with auditory stimuli.
- Investigating FFR's potential for assessing binaural processing is crucial.
Purpose of the Study:
- To determine if brainstem neural mechanisms for sound lateralization can be extracted from the FFR.
- To analyze how interaural time differences (ITDs) and intensity affect FFR.
- To explore FFR's utility in identifying normal and abnormal binaural processing.
Main Methods:
- Recorded monaural and binaural FFRs from normal-hearing subjects.
- Used low-frequency tone bursts with varying ITDs (0-667 µsec) and sound intensity levels (40-60 dB SL).
- Presented stimuli in concert and opposition to mimic lateralization.
Main Results:
- Overall intensity and ITDs differentially impacted FFR waveforms.
- FFRs evoked by ITDs and intensity variations were distinctly different.
- The binaural interaction component (BIC) remained largely unaffected by ITDs and intensity.
- Distinguishable FFR waveforms were observed for various ITDs and lateralization stimuli.
Conclusions:
- The FFR effectively distinguishes between different ITDs and lateralization stimuli.
- ITDs are critical cues for sound localization in mammals.
- The FFR shows potential as a tool for evaluating binaural processing in the lower brainstem.
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