Audiovisual speech perception in children with developmental language disorder in degraded listening conditions.
OBJECTIVE
The effect of the signal-to-noise ratio (SNR) on the perception of audiovisual speech in children with and without developmental language disorder (DLD) was investigated by varying the noise level and the sound intensity of acoustic speech. The main hypotheses were that the McGurk effect (in which incongruent visual speech alters the auditory speech percept) would be weaker for children with DLD than for controls and that it would get stronger with decreasing SNR in both groups.


METHODS
The participants were 8-year-old children with DLD and a sample of children with normal language development. In the McGurk stimuli, the consonant uttered by the voice differed from that articulated by the face. Three sound intensities (24, 36, and 48 dB) and noise levels (-12, 0, and +6 dB) were used. Perception of unisensory visual speech was also measured.


RESULTS
The children with DLD experienced a weak McGurk effect, that is, a weak influence of visual speech on audiovisual speech perception, which remained rather constant across SNR levels. The children with DLD were inaccurate at lipreading.


CONCLUSIONS
Children with DLD have problems in perceiving spoken consonants presented audiovisually and visually. The weaker McGurk effect could be accounted for by the poorer lipreading ability of children with DLD.
Niilo Mäki Institute, University of Jyväskylä, Finland. auli.meronen@elisanet.fi
Auli
A
Meronen
Kaisa
K
Tiippana
Jari
J
Westerholm
Timo
T
Ahonen
D000161:Acoustic Stimulation / Q000379:methods; D002648:Child; D002663:Child Language; D005260:Female; D006801:Humans; D007805:Language Development Disorders / Q000503:physiopathology*; D007807:Language Tests; D008085:Lipreading; D008144:Loudness Perception / Q000502:physiology; D008297:Male; D009622:Noise; D010700:Phonetics; D010775:Photic Stimulation / Q000379:methods; D059629:Signal-To-Noise Ratio; D013063:Speech Discrimination Tests; D013067:Speech Perception / Q000502:physiology*