An auditory, auditory electrophysiological and psycho-educational study of a population of hearing-impaired children

The thesis is proposed that when a child is assessed by behavioural measures and found to have a hearing loss, it is not implicit that the hearing acuity deficit is entirely peripheral in origin. Neither does it preclude the presence of any subtle central auditory dysfunction, which has not resulted in further loss in acuity. However, the presence of central auditory difficulties may well affect a child's ability to code and process auditory, and in particular, speech stimuli, in addition to the difficulties resulting from peripheral damage. Perceptual problems of this kind may therefore be present in hearing-impaired children who demonstrate excessive difficulty in the acquisition of oral language and related skills. The aim of this study was to examine the application of auditory electrophysiological (ep) measures to the differential diagnosis of children already identified as hearing-impaired, and to investigate the stated hypothesis. A test population of 36 hearing-impaired children, consisting of subsets of `good' and `poor' oral achievers of oral language, were assessed in three main areas: audiometric, auditory eps, and psycho-educational. Preparatory studies were carried out to ascertain optimum recording parameters for the auditory ep recordings in the main study, and for the collection of normative data. An associated experiment examining the relationship of high frequency hearing preservation and speech intelligibility was also carried out. The high frequency experiment necessitated several associated, preparatory experiments. Qualitative and quantitative analysis of the data was carried out and discussed. Findings here supported the hypothesis that the ep methods provide a suitable means of investigating the site of auditory dysfunction in hearing-impaired children, but there are unresolved difficulties in examining the locus, and effect, of additional central dysfunction in the presence of severe peripheral deficit. Some cases have been identified where there is a suspicion of central deficit, based on the ep findings, and compatible with the psycho-educational reports. Some unusual features in the ABR have been identified and their possible implications discussed. The results of the peripheral study on high frequency hearing supports the notion that an audiometric high frequency recovery contributes to speech intelligibility.