AVERAGE THRESHOLDS IN THE 8 TO 20 KHZ RANGE AS A FUNCTION OF AGE

The sound-pressure thresholds at the extended high frequencies of 8-20 kHz were measured for 65 normal subjects aged between 10 and 69 years . The results are not unlike those obtained by previous investigators. The thresholds increased gradually as a function of frequency, except around 12 kHz and above 19 kHz, and also as a function of age. To cla rify the connections between threshold, frequency and age, we introduc ed the regression lines for the threshold by anal ising two ranges of frequencies (8-10 kHz and 14-19 kHz) and determining their slopes and intercepts. The regression line analysis reveals that the thresholds a t 8-10 kHz tend to increase more at higher frequencies as subject age increased above 30 to 39 years, and those at 14-19 kHz increase transl ationally with increase of age. Our results did not contradict earlier reports on the pathological changes of the inner ear.