Open AccessCan we decode phonetic features in inner speech using surface electromyography?
Author(s) -
Ladislas Nalborczyk,
Romain Grandchamp,
Ernst H. W. Koster,
Marcela PerroneBertolotti,
Hélène Lœvenbruck
Publication year - 2020
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0233282
Subject(s) - speech production , covert , speech recognition , phonetics , psychology , motor theory of speech perception , neurocomputational speech processing , electromyography , speech perception , audiology , computer science , cognitive psychology , linguistics , perception , neuroscience , medicine , philosophy
Although having a long history of scrutiny in experimental psychology, it is still controversial whether wilful inner speech (covert speech) production is accompanied by specific activity in speech muscles. We present the results of a preregistered experiment looking at the electromyographic correlates of both overt speech and inner speech production of two phonetic classes of nonwords. An automatic classification approach was undertaken to discriminate between two articulatory features contained in nonwords uttered in both overt and covert speech. Although this approach led to reasonable accuracy rates during overt speech production, it failed to discriminate inner speech phonetic content based on surface electromyography signals. However, exploratory analyses conducted at the individual level revealed that it seemed possible to distinguish between rounded and spread nonwords covertly produced, in two participants. We discuss these results in relation to the existing literature and suggest alternative ways of testing the engagement of the speech motor system during wilful inner speech production.