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Published on: June 3, 2013
Masking by harmonic complexes in budgerigars (Melopsittacus undulatus).
M R Leek1, M L Dent, R J Dooling
1Army Audiology and Speech Center, Walter Reed Army Medical Center, Washington, D.C. 20307, USA.
The Journal of the Acoustical Society of America
|March 30, 2000
Summary
Budgerigar hearing differs from humans regarding auditory masking. Unlike humans, budgerigars showed minimal differences in masking effectiveness between positive and negative Schroeder-phase harmonic complexes, suggesting unique avian auditory processing.
Area of Science:
- Psychoacoustics
- Auditory Neuroscience
- Comparative Biology
Background:
- Auditory masking by harmonic complexes in humans depends on both frequency and phase spectrum.
- Harmonic complexes with modulated temporal waveforms typically cause less masking than those with flatter envelopes.
- Schroeder phases influence masking effectiveness, with negative Schroeder phases often causing more masking in humans.
Purpose of the Study:
- To investigate the masking effectiveness of harmonic complexes in budgerigars.
- To compare budgerigar masking thresholds with those of humans.
- To determine the role of phase spectrum in auditory masking in budgerigars.
Main Methods:
- Operant conditioning and the method of constant stimuli were used to assess pure-tone masking.
- Masking was examined using harmonic complexes with two different fundamental frequencies.
- Budgerigars' thresholds were measured at various masker levels.
Main Results:
- Budgerigar masking thresholds showed minimal differences between positive and negative Schroeder-phase waveforms.
- Positive Schroeder-phase complexes were more effective maskers in budgerigars, reversing the human effect.
- Phase selection was relevant, with coherent phases releasing from masking compared to random phases.
Conclusions:
- Psychoacoustic differences in auditory masking between budgerigars and humans may stem from peripheral auditory system variations.
- Differences in traveling wave mechanics and spectral tuning in avian versus mammalian auditory systems are implicated.
- This study highlights species-specific differences in auditory perception and processing.
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