This project aims to combine assessment of hearing abilities among subjects of different ages over time, together with information from their communication and health histories. Medical and cognitive data collected from subjects in the longitudinal study will be examined with respect to the audiologic and case history data. The two principal objectives of this project are: A) To study the contribution of medical, genetic, dietary and social factors to age-related auditory dysfunction; and B) To determine to what extent age, independent of other etiologic factors, causes a deterioration in hearing abilities. During the past year, approximately 450 subjects from the BLSA have been tested on all of the new measures in the hearing protocol. These measures include assessment of pure-tone hearing sensitivity, sentence understanding in noise, self-perceived hearing handicap, tympanometry, acoustic reflex thresholds, acoustic reflex magnitude, acoustic reflex adaptation, and acoustic reflex latency (the last five measures are part of the acoustic immittance battery of electrophysiologic tests). We have recently published a retrospective analysis of gender differences in longitudinal change in hearing sensitivity in a sample screened to exclude otological disorders and evidence of noise-induced hearing loss, and published a risk factor analysis showing that high blood pressure is associated with hearing loss in the speech frequencies (see Project Z01 AG 00638-06 LSB). We are now extending these analyses to develop age- and gender-specific nomograms for pure-tone thresholds and to identify modifiable risk factors for age-associated high-frequency hearing loss. Long range plans are to implement a collaboration with the National Temporal Bone Registry to study the relationship between inner ear pathology and longitudinal changes in audiological function, and to implement additional electrophysiological measures to provide corroborative evidence of the site of auditory system degeneration.
