Speech restoration: an interactive process.
OBJECTIVE
This study investigates the ability to understand degraded speech signals and explores the correlation between this capacity and the functional characteristics of the peripheral auditory system.


METHODS
The authors evaluated the capability of 50 normal-hearing native French speakers to restore time-reversed speech. The task required them to transcribe two-syllable items containing temporal reversions of variable sizes, ranging from no reversion to complete reversion, increasing by half-syllable steps. In parallel, the functionality of each participant's auditory efferent system was evaluated using contralateral suppression of click-evoked otoacoustic emissions.


RESULTS
Perceptual accuracy for time-reversed speech diminished when the size of the applied temporal distortion increased. A lexical benefit was evident, and an important interindividual variability in performance was observed. Functional exploration of the auditory system revealed that speech restoration performances correlated with the suppression strength of the participant's auditory efferent system.


CONCLUSIONS
These results suggest a clear relation between the functional asymmetry of the auditory efferent pathway (the right-side activity is greater than the left-side activity in right-handed participants) and the comprehension of acoustically distorted speech in normal-hearing participants. Further experiments are needed to better specify how the functionality of the medial olivocochlear bundle can cause phonological activation to be more efficient.
Grataloup
Claire
C
Centre National de la Recherche Scientifique (CNRS), UMR 5596, Université Lyon 2, Lyon, France. claire.grataloup@gmail.com
Hoen
Michel
M
Veuillet
Evelyne
E
Collet
Lionel
L
Pellegrino
François
F
Meunier
Fanny
F
D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D032882:Comprehension / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D017084:Otoacoustic Emissions, Spontaneous; D010700:Phonetics; D011571:Psychoacoustics; D013060:Speech; D013067:Speech Perception / Q000502:physiology*; D013997:Time Factors; D014825:Vocabulary; D055815:Young Adult