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Infant Auditory Processing and Event-related Brain Oscillations
Published on: July 1, 2015
Interaural fluctuations and the detection of interaural incoherence: bandwidth effects
Matthew J Goupell1, William M Hartmann
1Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA. goupellm@msu.edu
The Journal of the Acoustical Society of America
|July 15, 2006
Summary
Listeners can better detect sound incoherence not just by its level, but by fluctuations in interaural phase and level differences. These fluctuations, rather than coherence alone, predict detection performance, especially at wider bandwidths.
Area of Science:
- Auditory perception
- Psychoacoustics
- Signal processing
Background:
- Interaural coherence is a key cue for sound localization and spatial hearing.
- Previous research suggests coherence directly impacts the ability to discriminate auditory stimuli.
- The role of interaural fluctuations in detecting subtle incoherence requires further investigation.
Purpose of the Study:
- To investigate whether interaural coherence or interaural fluctuations predict the detection of slight sound incoherence.
- To examine the influence of bandwidth on the detectability of incoherence.
- To determine the primary acoustic cues listeners use to discriminate between coherent and incoherent noise.
Main Methods:
- Generated 100 left-right noise pairs with fixed long-term interaural coherence (0.9922) and varying bandwidths (14 Hz, 108 Hz, 2394 Hz).
- Tested listeners' ability to discriminate these noises from diotic (1.0 coherence) noises.
- Measured standard deviations of interaural phase and level differences to quantify fluctuations.
Main Results:
- Interaural coherence alone was an insufficient predictor of discrimination performance.
- Incoherence detection was strongly correlated with the magnitude of interaural phase and level difference fluctuations.
- Increasing bandwidth reduced variability in fluctuations and detection performance across noise pairs.
Conclusions:
- The detectability of auditory incoherence is primarily driven by the size of interaural fluctuations, not solely by the coherence value.
- Interaural fluctuation magnitude is a more robust predictor of incoherence detection than long-term coherence.
- Coherence value predicts performance only in the wideband limit, suggesting a shift in cue reliance with bandwidth.
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