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Features of across-frequency envelope coherence critical for comodulation masking release
Emily Buss1, John H Grose, Joseph W Hall
1Department of Otolaryngology/Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA. ebuss@med.unc.edu
The Journal of the Acoustical Society of America
|November 10, 2009
Summary
Masking release from coherent amplitude modulation is greatest with perfectly comodulated envelopes. Disrupting this envelope coherence harms masking release more when it occurs in flanking maskers than the on-signal masker.
Area of Science:
- Auditory perception
- Psychoacoustics
- Signal processing in hearing
Background:
- Masking release occurs when the envelope coherence of amplitude-modulated maskers is reduced.
- The degree of masking release depends on the envelope coherence across frequencies.
Purpose of the Study:
- To test if reducing envelope coherence has different effects depending on whether it occurs in the on-signal or flanking maskers.
- To investigate the role of unique envelope features in comodulation masking release.
Main Methods:
- Amplitude-modulated tones or noise bands were used as maskers, with a tone as the signal.
- Across-frequency masker coherence was manipulated by introducing modulation minima in on-signal or flanking masker envelopes.
- Experiments involved both ipsilateral and contralateral masker presentations.
Main Results:
- Disrupting modulation coherence had a more severe detrimental effect when modulation minima were introduced in flanking maskers compared to the on-signal masker.
- This effect was observed regardless of whether flanking maskers were presented ipsilaterally or contralaterally.
- Results suggest within-channel cues are not solely responsible for the observed masking release.
Conclusions:
- The cue for comodulation masking release relies on dynamic spectral features.
- Transient spectral peaks at the signal frequency, resulting from signal addition, are key to this phenomenon.
- The location of disrupted modulation coherence (on-signal vs. flanking) significantly impacts masking release effectiveness.
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