The role of non-auditory factors in measured and self-reported disability.
The effect of age per se on auditory disability in relation to other non-auditory factors, including personality and IQ, is unclear because of the close link with hearing threshold level. Auditory disability may be assessed in terms of either performance or self-report. It was measured using two tasks identifying words in sentences: (1) sentence identification in noise for spatially separated signal sources, and (2) identification of sensible and nonsensical sentences given at normal and artificially accelerated rates. Self-reported disability was assessed using the MRC Institute of Hearing Research's Hearing Disability Questionnaire and the American Hearing Performance Inventory. The sample of 240 individuals aged 50-75 years was constructed to provide a balance across the major stratification parameters of hearing level and age. In accordance with much of the published literature, the performance indices exhibited significant age effects: for a given hearing threshold level, older individuals are more disabled. Conversely, the indices of self-reported disability exhibit a trend whereby individuals with a given hearing threshold level, report a lower degree of disability with increasing age. There were no significant effects of personality, verbal or non-verbal IQ on the performance indices. However, these variables had large effects on reported disability, increasing the explained variance by approximately 20% more than the variance explained by hearing threshold level and age. Thus, the effect of age has the expected direction for performance-based disability, but for reported disability has the counter-intuitive direction. This finding, together with the additional large significant effects of other nonauditory variables, implies that indices of self-reported disability have to be controlled for these other major determinants if they are to be useful in an overall assessment of auditory disability.
Gatehouse
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MRC Institute of Hearing Research (Scottish Section), Glasgow Royal Infirmary, UK.
D000368:Aged; D000375:Aging / Q000523:psychology*; D001294:Attitude to Health; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold / Q000502:physiology; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007361:Intelligence Tests; D008297:Male; D008875:Middle Aged; D010551:Personality; D011304:Presbycusis / Q000175:diagnosis / Q000523:psychology*; D013063:Speech Discrimination Tests; D011795:Surveys and Questionnaires