Visual speechreading and cognitive performance in hearing-impaired and normal hearing children (11-14 years)

Background. Previous research has demonstrated that parts of the variation in adults' speechreading performance can be explained by the characteristics of some cognitive components. However, these results apply to populations of adults and less is known as to how results for populations of adults can be generalised to populations of children. Aim. This study aimed to examine cognitive and visual skills in a group of bilaterally, moderately hearing-impaired children and a group of normal hearing children and how these two skills relate to variability in speechreading of context-embedded sentences. Sample. Twenty-three hearing-impaired children (mean age: 12.7) and 23 normal hearing children (mean age: 12.5) matched for age, sex, verbal ability and school grades. The mean 'better ear' auditory threshold for the hearing-impaired was 44.8 dB. Results. The hearing-impaired children outperformed the normal hearing children on a sentence-based speechreading task and on a visual-visual word-decoding task, but not on a word-discrimination task. Differing from the case of adults, most cognitive tasks proved to be significantly related to sentence-based speechreading performance, where working memory capacity and visual word-decoding skill proved to be the strongest predictors. Conclusions. Speechreading is more cognitively demanding for children than for adults as they have not developed their cognitive abilities to the same extent as adults. Thus, they have to devote more processing capacity, relative to their total cognitive processing capacity, to the speechreading task. Skilled visual word-decoding and cognitive skills, together with everyday exposure to situations where speechreading is required, are some of the candidates for explanation of the hearing-impaired children's superior speechreading skill.