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The masking level difference for signals placed in masker envelope minima and maxima
Emily Buss1, Joseph W Hall, John H Grose
1Department of Otolaryngology/Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA. ebuss@med.unc.edu
The Journal of the Acoustical Society of America
|September 30, 2003
Summary
Masking Level Difference (MLD) research shows signal energy in masker minima is key for detection. This effect, stronger at higher masker levels, suggests physiological noise and temporal windows influence auditory perception.
Area of Science:
- Auditory Neuroscience
- Psychoacoustics
- Signal Processing
Background:
- Previous masking level difference (MLD) data suggest NoSpi detection relies on signal energy within masker envelope minima.
- This study investigates auditory perception of brief tonal signals within narrow-band noise maskers at various levels.
Purpose of the Study:
- To examine how signal timing relative to masker envelope minima or maxima affects detection thresholds.
- To investigate the influence of masker level on these detection differences.
- To explore the role of physiological noise and binaural temporal windows in auditory processing.
Main Methods:
- Used a 500-Hz tonal signal presented with a narrow-band Gaussian noise masker (50-Hz wide).
- Collected data at various masker levels, with signals coinciding with masker envelope maxima or minima.
- Employed two experiments: one with typical MLD stimuli and another minimizing spectral cues.
Main Results:
- A substantially larger MLD was observed for signals in masker minima compared to maxima at high masker levels.
- This difference was primarily driven by lower detection thresholds in masker minima.
- The effect diminished or disappeared at lower masker levels.
- Results were consistent across both stimulus types.
Conclusions:
- The observed level-dependent effects are consistent with physiological background noise and a level-dependent binaural temporal window.
- Basilar-membrane compression alone does not fully explain these findings.
- Auditory system's temporal processing and noise characteristics significantly impact signal detection.