Hearing loss due to aging (presbycusis).

Presbycusis is the progressive hearing loss caused by histologic changes due to aging. Schuknecht described four histopathologic types of presbycusis and correlated these findings to audiometric data. In a retrospective study, some strict criteria were set to distinguish the "pure" cases of presbycusis in a group of 1,181 subjects, 50 years of age and older, seen in our Audiology Clinic over one year; 91 subjects were found to meet these criteria. An attempt was made to fit the pure tone threshold curves into the types described by Schuknecht and correlate these curves to speech discrimination, tone decay, recruitment, age and sex of these subjects. It was found that: (a) only 50% of these audiograms could be fitted into the described histopathologic types, suggesting that in 50% of the subjects, presbycusis was caused by more than one degenerative process; (b) in 86% of subjects, speech discrimination was excellent or good in quiet; this test therefore may not reflect the difficulties presbycusis have in understanding speech under adverse auditory conditions; (c) subjects with flat pure tone threshold curves had generally good discrimination; (d) no differences were found between males and females; and (e) tests for tone decay and recruitment showed that in most cases the hearing loss was due to cochlear pathology, but these data do not exclude the possibility of central auditory involvement.