Auditory enhancement of increments in spectral amplitude stems from more than one source.

Samuele Carcagno, Catherine Semal, Laurent Demany
JARO. 2012-07-06; 13(5): 693-702
DOI: 10.1007/s10162-012-0339-y

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1. J Assoc Res Otolaryngol. 2012 Oct;13(5):693-702. doi: 10.1007/s10162-012-0339-y.
Epub 2012 Jul 6.

Auditory enhancement of increments in spectral amplitude stems from more than one
source.

Carcagno S(1), Semal C, Demany L.

Author information:
(1)University Bordeaux and CNRS, INCIA, 146 rue Léo Saignat, 33076, Bordeaux,
France.

A component of a test sound consisting of simultaneous pure tones perceptually
« pops out » if the test sound is preceded by a copy of itself with that component
attenuated. Although this « enhancement » effect was initially thought to be purely
monaural, it is also observable when the test sound and the precursor sound are
presented contralaterally (i.e., to opposite ears). In experiment 1, we assessed
the magnitude of ipsilateral and contralateral enhancement as a function of the
time interval between the precursor and test sounds (10, 100, or 600 ms). The
test sound, randomly transposed in frequency from trial to trial, was followed by
a probe tone, either matched or mismatched in frequency to the test sound
component which was the target of enhancement. Listeners’ ability to discriminate
matched probes from mismatched probes was taken as an index of enhancement
magnitude. The results showed that enhancement decays more rapidly for
ipsilateral than for contralateral precursors, suggesting that ipsilateral
enhancement and contralateral enhancement stem from at least partly different
sources. It could be hypothesized that, in experiment 1, contralateral precursors
were effective only because they provided attentional cues about the target tone
frequency. In experiment 2, this hypothesis was tested by presenting the probe
tone before the precursor sound rather than after the test sound. Although the
probe tone was then serving as a frequency cue, contralateral precursors were
again found to produce enhancement. This indicates that contralateral enhancement
cannot be explained by cuing alone and is a genuine sensory phenomenon.

DOI: 10.1007/s10162-012-0339-y
PMCID: PMC3441949
PMID: 22766695 [Indexed for MEDLINE]


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