Aging and auditory site of lesion.

The purpose of this study was to examine and quantify the functional auditory problems of presbycusis through a battery of recently developed diagnostic tests and to evaluate the usefulness of these tests with an elderly population. Diagnostic measures used were impedence measures, speech discrimination tests, synthetic sentence identification, compressed speech, two measures of tone decay, the short increment sensitivity index, a digit span test, and auditory brain stem response audiometry. Significant differences were found between scores for elderly subjects and those of young subjects who had similar audiograms. Use of the Metz test as an objective measure of recruitment yielded results suggesting a higher incidence of recruitment than evidenced by previous studies using loudness balancing procedures. The Olsen-Noffsinger procedure of quantifying tone decay revealed a greater difference between age groups than did the Suprathreshold Adaptation Test. Synthetic sentence identification revealed the most consistent age effect among the tests of central auditory function. Auditory brain stem response audiometry revealed several examples of abnormally long interpeak latencies. It is concluded that there is both behavioral and electrophysiological evidence of central and peripheral auditory disorder frequently accompanying senescence.