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Hemispheric Asymmetries in Speech Perception: Sense, Nonsense and Modulations

Rosen, S; Wise, RJS; Chadha, S; Conway, EJ; Scott, SK; (2011) Hemispheric Asymmetries in Speech Perception: Sense, Nonsense and Modulations. PLOS ONE , 6 (9) , Article e24672. 10.1371/journal.pone.0024672. Green open access

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Abstract

Background: The well-established left hemisphere specialisation for language processing has long been claimed to be based on a low-level auditory specialization for specific acoustic features in speech, particularly regarding 'rapid temporal processing'.Methodology: A novel analysis/synthesis technique was used to construct a variety of sounds based on simple sentences which could be manipulated in spectro-temporal complexity, and whether they were intelligible or not. All sounds consisted of two noise-excited spectral prominences (based on the lower two formants in the original speech) which could be static or varying in frequency and/or amplitude independently. Dynamically varying both acoustic features based on the same sentence led to intelligible speech but when either or both acoustic features were static, the stimuli were not intelligible. Using the frequency dynamics from one sentence with the amplitude dynamics of another led to unintelligible sounds of comparable spectro-temporal complexity to the intelligible ones. Positron emission tomography (PET) was used to compare which brain regions were active when participants listened to the different sounds.Conclusions: Neural activity to spectral and amplitude modulations sufficient to support speech intelligibility (without actually being intelligible) was seen bilaterally, with a right temporal lobe dominance. A left dominant response was seen only to intelligible sounds. It thus appears that the left hemisphere specialisation for speech is based on the linguistic properties of utterances, not on particular acoustic features.

Type: Article
Title: Hemispheric Asymmetries in Speech Perception: Sense, Nonsense and Modulations
Open access status: An open access version is available from UCL Discovery
DOI: 10.1371/journal.pone.0024672
Publisher version: http://dx.doi.org/10.1371/journal.pone.0024672
Language: English
Additional information: © 2011 Rosen et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. S.K.S. is funded by Grant No. WT074414MA from the Wellcome Trust. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Keywords: HUMAN AUDITORY-CORTEX, TEMPORAL ENVELOPE, HUMAN BRAIN, CUES, LATERALIZATION, SENSITIVITY, ACTIVATION, AMPLITUDE, POSITION, FEATURES
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Div of Psychology and Lang Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Div of Psychology and Lang Sciences > Institute of Cognitive Neuroscience
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Div of Psychology and Lang Sciences > Speech, Hearing and Phonetic Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/1326272
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