The Effect of Static Air Pressure in the External Auditory Meatus on Hearing Acuity

Abstract

The specific purposes of this study were to determine the effects of various static air pressures in the external auditory meatus on (1) threshold sensitivity and (2) hearing acuity at two loudness levels above threshold. To determine the effect of a pressure differential across the tympanic membrane on the threshold sensitivity, measurements were obtained by the Method of Adjustment for 10 ears at each of 41 frequencies (from 100 to 8000 cps) at each of four pressure conditions (−10, −20, +10, +20 cm H2O). For all pressures used threshold sensitivity was generally decreased for frequencies below 1500 cps. with a slight increase in sensitivity for frequencies between 1500 and 2300 cps and a general decrease in sensitivity for frequencies between 2300 and 8000 cps. To test the effect of pressure on loudness, five subjects made equal loudness balance judgments for six frequencies (200, 400, 1000, 1600, and 4000 cps) at 30 db and at 60 db above threshold under each of the four experimental pressure conditions. As in the threshold sensitivity study results indicated a general decrease in sensitivity for frequencies below 1000 cps and only slight effects on the higher frequencies. The effect of static pressure on speech intelligibility was also studied and in the range investigated was found negligible. This work was done at Ohio State University.