Aging changes in human auditory discriminating thresholds and hearing thresholds

Measurements of auditory discriminating thresholds of frequency (△f),phase (△φ) and intensity (△I) of repetitive clicks and hearing thresholds (HT) of pure tones were performed in human subjects with no history of ear pathology,the range of age being 17-67 years.The ref erence repetition rate of the clicks used was 500 pps and the frequencies for pure tone audiolnetry were 500-8000 Hz in octave steps.Aging changes of △f,△φ,△I and HT are obvious after the age of 40,while before 40,only △φ,△I and HT of 8 kHz show mild but statistically significant in-crease with age.Calculated on the basis of the 50 percentile curves from the experimental results (N=190),formulae of these aging changes can be expressed as:△f=0.0024X²-0.116X+2.116(pps),△φ=0.0010X²-0.050X+1.343(degrees),△I=0.0004X²-0.016X+0.455(dB) and,for 8000 Hz pure tone,HT=0.0424X²-2.15X+34.94(dB nHL).