Cortical tracking of a background speaker modulates the comprehension of a foreground speech signal
File(s)
Published version
Author(s)
Keshavarzi, Mahmoud
Varano, Enrico
Reichenbach, Johann
Type
Journal Article
Abstract
Understanding speech in background noise is a difficult task. The tracking of speech rhythms such as the rate of syllables and words by cortical activity has emerged as a key neural mechanism for speech in-noise comprehension. In particular, recent investigations have used transcranial alternating current stimulation (tACS) with the envelope of a speech signal to influence the cortical speech tracking, demonstrating that this type of stimulation modulates comprehension and therefore evidencing a functional role of the cortical tracking in speech processing. Cortical activity has been found to track the rhythms of a background speaker as well, but the functional significance of this neural response remains unclear. Here we employ a speech-comprehension task with a target speaker in the presence of a distractor voice to show that tACS with the speech envelope of the target voice as well as tACS with the envelope of the distractor speaker both modulate the comprehension of the target speech. Because the envelope of the distractor speech does not carry information about the target speech stream, the modulation of speech comprehension through tACS with this envelope evidences that the cortical tracking of the background speaker affects the comprehension of the foreground speech signal. The phase dependency of the resulting modulation of speech comprehension is, however, opposite to that obtained from tACS with the envelope of the target speech signal. This suggests that the cortical tracking of the ignored speech stream and that of the attended speech stream may compete for neural resources.
Date Issued
2021-06-09
Date Acceptance
2021-04-12
Citation
The Journal of Neuroscience, 2021, 41 (23), pp.5093-5101
ISSN
0270-6474
Publisher
Society for Neuroscience
Start Page
5093
End Page
5101
Journal / Book Title
The Journal of Neuroscience
Volume
41
Issue
23
Copyright Statement
© 2021 Keshavarzi et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license, which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.
Sponsor
Engineering & Physical Science Research Council (E
Engineering & Physical Science Research Council (EPSRC)
US Army (US)
Engineering & Physical Science Research Council (EPSRC)
Grant Number
EP/M026728/1
EP/R032602/1
W911NF1910396
EP/T020970/1
Subjects
auditory
background speech
cortical tracking
selective attention
tACS
Neurology & Neurosurgery
11 Medical and Health Sciences
17 Psychology and Cognitive Sciences
Publication Status
Published