Frequency-shift detectors bind binaural as well as monaural frequency representations.
Journal of Experimental Psychology: Human Perception and Performance. 2011-01-01; 37(6): 1976-1987
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1. J Exp Psychol Hum Percept Perform. 2011 Dec;37(6):1976-87. doi: 10.1037/a0024321.
Epub 2011 Jul 4.
Frequency-shift detectors bind binaural as well as monaural frequency
Carcagno S(1), Semal C, Demany L.
(1)Institut de Neurosciences Cognitives et Integratives d’Aquitaine, Universite
de Bordeaux, France.
Previous psychophysical work provided evidence for the existence of automatic
frequency-shift detectors (FSDs) that establish perceptual links between
successive sounds. In this study, we investigated the characteristics of the FSDs
with respect to the binaural system. Listeners were presented with sound
sequences consisting of a chord of pure tones followed by a single test tone. Two
tasks were performed. In the « present/absent » task, the test tone was either
identical to one of the chord components or positioned halfway in frequency
between two components, and listeners had to discriminate between these two
possibilities. In the « up/down » task, the test tone was slightly different in
frequency from one of the chord components and listeners had to identify the
direction (up or down) of the corresponding shift. When the test tone was a pure
tone presented monaurally, either to the same ear as the chord or to the opposite
ear, listeners performed the up/down task better than the present/absent task.
This paradoxical advantage for directional frequency shifts, providing evidence
for FSDs, persisted when the test tone was replaced by a dichotic stimulus
consisting of noise but evoking a pitch sensation as a consequence of binaural
processing. Performance in the up/down task was similar for the dichotic stimulus
and for a monaural narrow-band noise matched in pitch salience to it. Our results
indicate that the FSDs are insensitive to sound localization mechanisms and
operate on central frequency representations, at or above the level of
convergence of the monaural auditory pathways.
PMID: 21728457 [Indexed for MEDLINE]