The role of across-frequency processes in dichotic listening conditions.
In the bandwidening experiment with a diotic noise masker, an apparently wider critical bandwidth has often been reported when a dichotic signal (Spi) is used instead of a diotic signal (So). Two competing across-channel processes were proposed to account for this apparently wider critical bandwidth: (i) A detrimental across-channel effect reducing the binaural masking-level difference (BMLD) for broadband maskers and (ii) a beneficial integration of information across channels for narrowband maskers. The two hypotheses result in different predictions of the BMLD in the notched-noise experiment: According to the first hypothesis, the change in BMLD with notch width is determined by the level-dependence of the BMLD for a narrowband masker centered at the signal frequency, whereas the second hypothesis predicts that it is determined by the level-dependence of the BMLD for a broadband masker. To test the hypotheses, masked thresholds of a diotic or dichotic 500-Hz signal were measured for a diotic notched-noise masker as a function of notch width. In addition, thresholds were measured for a diotic broadband and narrowband masker as a function of masker level. The data indicate that neither of the two hypotheses is able to predict the continuous decrease in the BMLD as the notch width increases.
Nitschmann
Marc
M
International Graduate School Neurosensory Science and Systems, Carl-von-Ossietzky-Universitat Oldenburg, 26111 Oldenburg, Germany. marc.nitschmann@uni-oldenburg.de
Verhey
Jesko L
JL
Kollmeier
Birger
B
D000161:Acoustic Stimulation; D000328:Adult; D001307:Auditory Perception; D001309:Auditory Threshold; D004007:Dichotic Listening Tests; D004423:Ear; D005260:Female; D006801:Humans; D008297:Male; D008959:Models, Neurological; D009622:Noise; D010470:Perceptual Masking; D011571:Psychoacoustics; D017603:Signal Detection, Psychological; D055815:Young Adult