Auditory processing in children : a study of the effects of age, hearing impairment and language impairment on auditory abilities in children

In this thesis we tested the hypotheses that the auditory system of children continues to mature until at least the age of 12 years and that the development of auditory processing in hearing-impaired and language-impaired children is often delayed or even genuinely disturbed. Data from a longitudinal study in 6- to 12-year-old normally developing children suggested that maturational effects play an important role in auditory processing (at least) up to the age of 12 years. A group of 6- to 8-year-old language-impaired children was found to score significantly poorer on the same test battery. Many of the basic auditory processing measures in our test battery correlated significantly with receptive and expressive language scores. We found that an auditory test battery adapted to younger children could be administered successfully to children aged 4 to 6 years. Most tests again showed a clear effect of chronological age. A separate study on measures of binaural hearing in a group of 12-year-old children who had suffered from prolonged predominantly unilateral otitis media with effusion (OME) between the age of 2 and 4 years did not support the notion that long-term auditory processing deficits can be the result of early asymmetrical OME in children. The effect of time compression and time expansion of speech on speech perception in noise was examined in 9- to 12-year-old hearing-impaired and language-impaired children. Both groups of children were found to have significantly higher speech recognition thresholds in noise (SRTN) than their normal peers. SRTN tended to be influenced to a greater extent by time compression in both impaired groups compared to the control group. The research presented in this thesis may enable the early diagnosis of auditory processing disorders in children. Early intervention could prevent or at least diminish the negative effects of an auditory processing disorder on language development