Implicit versus explicit frequency comparisons: two mechanisms of auditory change detection.
Listeners had to compare, with respect to pitch (frequency), a pure tone (T) to a combination of pure tones presented subsequently (C). The elements of C were either synchronous, and therefore difficult to hear out individually, or asynchronous and therefore easier to hear out individually. In the "present/absent" condition, listeners had to judge if T reappeared in C or not. In the "up/down" condition, the task was to judge if the element of C most similar to T was higher or lower than T. When the elements of C were synchronous, the up/down task was found to be easier than the present/absent task; the converse result was obtained when the elements of C were asynchronous. This provides evidence for a duality of auditory comparisons between tone frequencies: (1) implicit comparisons made by automatic and direction-sensitive "frequency-shift detectors"; (2) explicit comparisons more sensitive to the magnitude of a frequency change than to its direction. Another experiment suggests that although the frequency-shift detectors cannot compare effectively two tones separated by an interfering tone, they are largely insensitive to interfering noise bursts.
Demany
Laurent
L
Centre National de la Recherche Scientifique,, Université de Bordeaux, Bordeaux, France. laurent.demany@u-bordeaux2.fr
Semal
Catherine
C
Pressnitzer
Daniel
D
D000161:Acoustic Stimulation; D000328:Adult; D001307:Auditory Perception; D004192:Discrimination, Psychological; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term; D008875:Middle Aged; D010897:Pitch Discrimination; D010898:Pitch Perception; D013997:Time Factors