Frequency resolution as a function of hearing threshold level and age.

Frequency resolution ability was measured using a psychoacoustical tuning curve (PTC) or a notch-noise technique in two population samples. The first sample incorporated 1764 subjects with various degrees of sensorineural hearing impairment and ranging in age from 17-80 years. The second sample included 240 subjects aged between 50 and 75 years, carefully balanced in terms of impairment and age to avoid confounding between these two variables. In both samples, frequency resolution ability declined with increasing hearing threshold level (HTL), as measured by either method. In a subsample tested with both methods, the correlation between the two was only modest. After accounting for HTL, there was a minor dependence of frequency resolution on age, older subjects having poorer frequency resolution once HTL had been accounted for. No addition to the explained variance was achieved by taking sex, occupational group, or audiogram slope into account. Despite the documented reproducibility of the measures, much of the variance in the frequency resolution measurements remained unrelated to HTL or age.