Audiovisual Speech Perception in Brazilian Portuguese-speaking Children with and without Speech Sound Disorder (SSD)

This study compared single modality and audiovisual (crossmodally congruent and incongruent) speech perception performance in Brazilian Portuguese-speaking children with and without SSD. Thirty-six children (17 with and 19 without SSD; average age = 6;7) participated in an adapted syllable identification test. The auditory and visual stimuli consisted of monosyllabic consonant-vowel utterances involving [p,b,t,d,k,g,f,v,s,z,ʃ,ʒ,m,n,ɲ,l,ʎ,ɾ,χ,w], produced in the context of [a] vowel. The stimuli were presented in different modality conditions: auditory-only (AO), visual-only (VO), audio-visual congruent (AV+), and audio-visual incongruent (AV-). As expected, SSD children presented lower accuracy than TD children, but the prediction that SSD children show less audiovisual integration was not confirmed. Compared to typically developing children, children with SSD demonstrate lower perceptual accuracy across all modalities, not restricted to the visual domain. SSD children showed correlations between perceptual accuracy with age and severity level, highlighting a distinct developmental pattern relative to TD children. There was no difference between the groups on visual gain benefited from congruent visual (lipread) cues, nor on the McGurk illusion, though both groups displayed the illusion. Therefore, SSD children show reduced perceptual accuracy across sensory modalities and a distinct developmental profile associated with age and severity. Nonetheless, audiovisual speech perception appears preserved, underscoring the importance of integrated intervention frameworks that account for the interaction between perceptual abilities, developmental trajectories, and clinical severity in the characterization and management of SSD.