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Comodulation masking release for three types of modulator as a function of modulation rate
R P Carlyon1, S Buus, M Florentine
1Communication Research Lab, Northeastern University, Boston, Massachusetts.
Hearing Research
|October 1, 1989
Summary
Comodulation Masking Release (CMR) was studied using modulated noise maskers. CMR varied with modulator type but not systematically with envelope frequency, showing smaller values for sinusoidal modulation.
Area of Science:
- Auditory perception
- Psychoacoustics
- Signal processing
Background:
- Comodulation Masking Release (CMR) is crucial for understanding auditory perception.
- Investigating the influence of modulator type and frequency on CMR is essential.
Purpose of the Study:
- To examine how modulator type and frequency affect Comodulation Masking Release (CMR).
- To determine the relationship between envelope frequency (fe) and modulator type in auditory masking.
Main Methods:
- Measured auditory thresholds for a 4-kHz tone masked by various modulated and unmodulated noise types.
- Utilized square wave, sine wave, and lowpass noise modulators at different frequencies.
- Defined CMR by comparing modulated-unmodulated differences across different masking conditions.
Main Results:
- Masking thresholds decreased with modulation, except at high envelope frequencies (fe).
- Modulated-Unmodulated Difference (MUD) decreased as fe increased.
- CMR was generally smaller for sinusoidal modulation compared to square-wave or lowpass-noise modulation.
Conclusions:
- CMR is dependent on modulator type, with sinusoidal modulation yielding smaller effects.
- CMR did not show a systemic variation with envelope frequency for the tested 4-kHz signals.
- The study provides insights into the spectral and temporal processing of auditory signals.