Mice and humans perceive multiharmonic communication sounds in the same way

Günter Ehret* and Sabine Riecke‡

Proc Natl Acad Sci USA 2002 Jan 8;99(1):479-82

*Department of Neurobiology, University of Ulm, D-89069 Ulm, Germany; and ‡Department of Biology, University of Konstanz, D-78457 Konstanz, Germany
Edited by Michael M. Merzenich, University of California, San Francisco, CA, and approved November 8, 2001 (received for review July 16, 2001)

Abstract:

Vowels and voiced consonants of human speech and most mammalian vocalizations consist of harmonically structured sounds. The frequency contours of formants in the sounds determine their spectral shape and timbre and carry, in human speech, important phonetic and prosodic information to be communicated. Steady-state partitions of vowels are discriminated and identified mainly on the basis of harmonics or formants having been resolved by the critical-band filters of the auditory system and then grouped together. Speech-analog processing and perception of vowel-like communication sounds in mammalian vocal repertoires has not been demonstrated so far. Here, we synthesize 11 call models and a tape loop with natural wriggling calls of mouse pups and show that house mice perceive this communication call in the same way as we perceive speech vowels: they need the presence of a minimum number of formants (three formants-in this case, at 3.8 + 7.6 + 11.4 kHz), they resolve formants by the critical-band mechanism, group formants together for call identification, perceive the formant structure rather continuously, may detect the missing fundamental of a harmonic complex, and all of these occur in a natural communication situation without any training or behavioral constraints. Thus, wriggling-call perception in mice is comparable with unconditioned vowel discrimination and perception in prelinguistic human infants and points to evolutionary old rules of handling speech sounds in the human auditory system up to the perceptual level.
(Bold text emphasis by Martin Braun)

Comment:

In a series of elegant experiments with untrained and freely behaving mice, Ehret and Riecke showed that these animals perceive pitch in a similar way as cats, non-human primates, and humans. We now know that also mice group consecutive harmonics for the perception of one unitary pitch. Of particular interest is the finding that also in these small mammals the grouping of harmonics is governed by the critical bandwidth, which is hardwired in the auditory midbrain (inferior colliculus). The molecular mechanism of pitch neurons in this nucleus can now be investigated by the established techniques of gene analysis, which are already highly developed for the mouse. (Comment Martin Braun)

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