Don't speak too fast! Processing of fast rate speech in children with specific language impairment.

Hélène Guiraud,Sonia Krifi-Papoz,Vania Herbillon,Sibylle Gonzalez-Monge,Aurélia Caillot-Bascoul,Nathalie Bedoin,Véronique Boulenger,Sonja Kotz

doi:10.1371/journal.pone.0191808

Abstract

BackgroundPerception of speech rhythm requires the auditory system to track temporal envelope fluctuations, which carry syllabic and stress information. Reduced sensitivity to rhythmic acoustic cues has been evidenced in children with Specific Language Impairment (SLI), impeding syllabic parsing and speech decoding. Our study investigated whether these children experience specific difficulties processing fast rate speech as compared with typically developing (TD) children.MethodSixteen French children with SLI (8–13 years old) with mainly expressive phonological disorders and with preserved comprehension and 16 age-matched TD children performed a judgment task on sentences produced 1) at normal rate, 2) at fast rate or 3) time-compressed. Sensitivity index (d′) to semantically incongruent sentence-final words was measured.ResultsOverall children with SLI perform significantly worse than TD children. Importantly, as revealed by the significant Group × Speech Rate interaction, children with SLI find it more challenging than TD children to process both naturally or artificially accelerated speech. The two groups do not significantly differ in normal rate speech processing.ConclusionIn agreement with rhythm-processing deficits in atypical language development, our results suggest that children with SLI face difficulties adjusting to rapid speech rate. These findings are interpreted in light of temporal sampling and prosodic phrasing frameworks and of oscillatory mechanisms underlying speech perception.

Highlights

Every listener has noticed how speech rate can vary considerably between speakers and contexts and how this can be challenging, at least in the first minutes of a conversation
Overall children with Specific Language Impairment (SLI) perform significantly worse than typically developing (TD) children
In agreement with rhythm-processing deficits in atypical language development, our results suggest that children with SLI face difficulties adjusting to rapid speech rate

Summary

Introduction

Every listener has noticed how speech rate can vary considerably between speakers and contexts and how this can be challenging, at least in the first minutes of a conversation. Articulatory gestures are achieved more quickly and less accurately, resulting in reduction phenomena, enhanced coarticulation (i.e., increased gestural overlap) and assimilation, which may even lead to the suppression of whole segments [2] These changes operate nonlinearly, partly because of articulatory restrictions [3]: in English and French for instance, consonants and stressed syllables (in English) are less reduced than vowels and unstressed syllables [4,5]. Such spectro-temporal modifications typically occur in naturally accelerated speech, whereas the spectral and pitch content in time-compressed speech – an artificial reduction of signal duration often used in experimental phonetics – remain intact. Our study investigated whether these children experience specific difficulties processing fast rate speech as compared with typically developing (TD) children

Methods

Discussion

Conclusion