Enhancement of increments in spectral amplitude: further evidence for a mechanism based on central adaptation.
Advances in Experimental Medicine and Biology. 2013-01-01; : 175-182
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1. Adv Exp Med Biol. 2013;787:175-82. doi: 10.1007/978-1-4614-1590-9_20.
Enhancement of increments in spectral amplitude: further evidence for a mechanism
based on central adaptation.
Carcagno S(1), Semal C, Demany L.
(1)Université de Bordeaux, Bordeaux, France.
The threshold for detecting a tone in a multitone masker is lower when the
masker-plus-signal stimulus is preceded by a copy of the masker. One potential
explanation of this « enhancement » phenomenon is that the -precursor stimulus acts
as a « template » of the subsequent masker, thus helping listeners to segregate the
signal from the masker. To assess this idea, we measured enhancement for
precursors that were perceptually similar to the masker and for precursors that
were made dissimilar to the masker by gating their components asynchronously. We
found that the two types of precursor produced similar amounts of enhancement.
This was true not only when the precursor and the subsequent test stimulus were
presented to the same ear but also when they were presented to opposite ears. In
a second experiment, we checked that the precursors with asynchronously gated
components were perceptually poor templates of the subsequent maskers. Listeners
now had to discriminate between test stimuli -containing the same components as
the precursor and test stimuli containing all but one of the precursor
components. We found that in this experimental situation, where enhancement could
play no role, gating the precursor components asynchronously disrupted
performance. Overall, our results are inconsistent with the hypothesis that
precursors producing enhancement are beneficial because they are used as
perceptual templates of the masker. Our results are instead consistent with an
-explanation of enhancement based on selective neural adaptation taking place at
a central locus of the auditory system.
PMID: 23716222 [Indexed for MEDLINE]