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Vertical-plane sound localization probed with ripple-spectrum noise
Ewan A Macpherson1, John C Middlebrooks
1Kresge Hearing Research Institute, University of Michigan, 1301 East Ann Street, Ann Arbor, Michigan 48109-0506, USA. emacpher@umich.edu
The Journal of the Acoustical Society of America
|July 26, 2003
Summary
Listeners utilize specific spectral details for sound localization. Fine spectral details (finer than 2 ripples/octave) and broad spectral variations (coarser than 0.5 ripples/octave) minimally impact vertical-plane sound localization accuracy.
Area of Science:
- Auditory Perception
- Psychoacoustics
- Acoustic Signal Processing
Background:
- Vertical-plane sound localization relies on spectral cues.
- Understanding the scale of spectral detail is crucial for auditory perception research.
Purpose of the Study:
- Investigate the scale of spectral detail listeners use for vertical-plane localization.
- Determine how ripple density, depth, and phase affect spectral cue interpretation.
Main Methods:
- Free-field localization judgments using noise bursts with log-ripple spectra.
- Varied ripple density (0.5-2 ripples/octave), peak-to-trough depth (≥20 dB), and phase.
- Measured localization error rates and accuracy.
Main Results:
- Localization error rates increased most for ripple densities between 0.5-2 ripples/octave.
- Accuracy degraded significantly only for ripple depths ≥20 dB.
- Listener responses to ripple phase varied, with some errors unrelated to phase.
Conclusions:
- Spectral details finer than 2 ripples/octave or coarser than 0.5 ripples/octave minimally influence spectral cue processing for sound localization.
- Broad-scale spectral variations are discounted despite their contribution to directional transfer functions.
- The findings refine our understanding of the spectral resolution limits in auditory localization.