Factors associated with individual differences in clinical measures of speech recognition among the elderly

In the present study, the speech-recognition performance of 50 subjects aged 63 to 83 years was measured for a wide range of materials (nonsense syllables, monosyllabic words, sentences) and listening conditions (presentation levels of 70 and 90 dB SPL, both in quiet and in a noise background). In addition to complete audiologic evaluations, measures of auditory processing (the Test of Basic Auditory Capabilities [TBAC], Watson, 1987) and cognitive function (Wechsler Adult Intelligence Scale-Revised [WAIS-R], and the Wechsler Memory Scale-Revised [WMS-R], Wechsler, 1981, 1987) were obtained from all subjects. Principal component analyses were applied to each of the three sets of measures (speech-recognition, auditory, and cognitive) prior to examining associations among the sets using canonical analyses. Two principal components captured most of the systematic variation in performance sampled by the set of 20 speech-recognition measures. Hearing loss emerged as the single largest factor associated with individual differences in speech-recognition performance among the elderly, accounting for 70-75% of the total variance in speech-recognition performance, with the measures of auditory processing and cognitive function accounting for little or no additional variance.