Observations on masking in puretone audiometry

Summary

When the difference in hearing between the two ears is of some considerable degree, it is essential to block the betterhearing ear by a masking device, for accurate estimation of the threshold of hearing of the bad ear. In air conduction tests, when the difference in thresholds of the two ears exceeds 50 db the better ear should be excluded by masking. In bone conduction tests, the untested ear should always be excluded by an air conducted masking sound. Appropriate masking levels must be determined during the course of the test by Zwislocki method and the maximum usable masking level should not be exceeded during the tests. White noise is a better masking sound than pure tones. “Paracussis Willist” is only apparent improvement of hearing in a noisy place, these patients deriving benefit only by the raising of the speaker’s voice.