Comparison of Threshold Data Obtained by the Method of Limits and the Method of Adjustment

Abstract

One of the major areas of emphasis in contemporary audiology is the development of audiometric techniques for dealing with clinical problems related to permanent hearing impairments. However, few studies have been conducted which attempt to establish the relationship of threshold values obtained under the various testing conditions. The present paper describes the results obtained for 105 subjects monaurally tested in an anechoic chamber on a modified ADC audiometer and a Békésy-type audiometer. A comparison of test results for nine frequencies between 250 cps and 8000 cps for each ear shows statistically significant differences in mean threshold sound pressure levels for nearly all frequencies, with the ADC values lower in most instances. Likewise, statistically significant differences in the variability of threshold values were obtained at all but one frequency below 2000 cps, with variability less in the ADC values. There also appears to be a general tendency for the product-moment correlation between ADC and Békésy threshold values to increase with an increase in the frequency of the testing tone. These findings obtain whether the Békésy-type audiograms are read using a “midpoint curve” or a “peak curve” to provide the threshold data. Although no significant differences in the variability of “midpoint” and “peak” Békésy threshold values were obtained at any frequency for either ear, all differences in mean threshold sound pressure levels are statistically significant. The results of the study clearly reveal the effects of testing method on mean thresholds of hearing and indicate the need for the standardization of procedures in large-scale hearing tests. This work was supported by the U. S. Air Force.