The contribution of central auditory factors to auditory disability.

Auditory disability increases with both hearing threshold level and age. It is often suggested that some or most of the age effect in auditory disability is underpinned by deficits in central auditory function. A sample of 240 individuals aged between 50 and 75 years was examined to provide a balance across the major variables of hearing level and age. The central auditory indices investigated were: the binaural masking difference, the effects of dichotic competition on the staggered spondaic word tests, the binaural advantage for dichotically presented words, the binaural advantage for dichotically presented sentences, the effect of increasing the rate of presentation of speech, and the effect of nonsense as opposed to sensible sentences. In addition, the non-auditory variables of verbal and non-verbal IQ and the peripheral auditory factors of frequency and temporal resolution were assessed. Auditory disability was assessed using a performance index derived from a sentence identification-in-noise procedure and a procedure containing sense or nonsense sentences. Aspects of self-reported disability were determined using the MRC Institute of Hearing Research's Hearing Disability Questionnaire and the American Hearing Performance Inventory. There were significant correlations between the derived central variables and measured disability after control for hearing threshold levels and age. Central variables were correlated with self-reported disability for only the specific sub-score reflecting disability in localisation. On a multiple regression, the central variables explained 11.1% of the variance in performance index of disability above the 21.1% explained by hearing threshold levels and age.(ABSTRACT TRUNCATED AT 250 WORDS)