The role of non—auditory factors in measured and self—reported disability

Abstract

Gatehouse S. The role of non—auditory factors in measured and self—reported disability. Acta Otolaryngol (Stockh) 1991; Suppl. 476: 249—256.

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 artifically 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.

Key Words:

• disability
• ageing
• personality
• IQ