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Diotic and dichotic detection using multiplied-noise maskers
1IPO Center for Research on User-System Interaction, Eindhoven, The Netherlands.
The Journal of the Acoustical Society of America
|May 5, 1998
Summary
This study investigated binaural masking level differences (BMLDs) using a novel multiplied-noise masker. Results show BMLDs can reach 30 dB for interaural intensity differences, varying with masker bandwidth and frequency.
Area of Science:
- Auditory Neuroscience
- Psychoacoustics
- Signal Processing
Background:
- Binaural masking level differences (BMLDs) are crucial for sound localization.
- Traditional Gaussian noise maskers have limitations in studying BMLDs.
Purpose of the Study:
- To investigate BMLDs using a multiplied-noise masker.
- To examine the effects of masker bandwidth and center frequency on BMLDs.
- To compare BMLDs generated by multiplied-noise versus Gaussian noise.
Main Methods:
- Detection thresholds were measured using a multiplied-noise masker with in-phase presentation.
- Sinusoidal signals were presented in-phase (NoSo) or out-of-phase (NoS pi).
- Stimulus properties were manipulated to isolate interaural time delays (ITDs) and interaural intensity differences (IIDs).
Main Results:
- Narrow-band BMLDs reached 30 dB for the IID condition (theta = 0) at 4 kHz.
- BMLDs for the IID condition were frequency-independent, unlike with Gaussian noise.
- For the ITD condition (theta = pi/2), BMLDs were limited to frequencies below 2 kHz with narrow-band maskers but reached 15 dB at 4 kHz with wider maskers.
Conclusions:
- Multiplied-noise maskers provide a unique way to study BMLDs, particularly IIDs.
- Stimulus compression before binaural interaction may explain frequency-dependent BMLDs.
- Findings offer insights into the mechanisms of binaural hearing.