AGE-SPECIFIC AND GENDER-SPECIFIC REFERENCE RANGES FOR HEARING LEVEL AND LONGITUDINAL CHANGES IN HEARING LEVEL

This paper presents age-specific reference ranges for hearing level an d change in hearing level for men and women at 500, 1000, 2000, and 40 00 Hz. The percentiles are constructed from data obtained from persons in the Baltimore Longitudinal Study of Aging who were rigorously scre ened for otological disorders and evidence of noise-induced hearing lo ss. The resulting percentile curves represent norms for changes in hea ring level in the absence of any known otologic disease. These percent ile curves provide a reference for detecting when a person deviates fr om a normal pattern of change, thus helping in diagnosing problems wit h hearing or in monitoring hearing in occupational settings. The smoot hed means and standard deviations of the hearing levels were used to c onstruct the longitudinal percentiles. The percentiles for cross-secti onal change were constructed using the skew normal distribution to all ow for the percentiles to be asymmetric on either side of the median l evel. These percentiles are the first reference curves that (1) provid e standards for hearing level changes over periods of up to 15 years, (2) account for age differences in the distribution of hearing levels, and (3) are based on data from persons who have been systematically s creened for otological disorders and evidence of noise-induced hearing loss. (C) 1996 Acoustical Society of America.