How to eliminate air-bone gaps audiometrically: use too much masking.

The excessive, indiscriminate use of masking during measurements of pure-tone bone-conduction thresholds can reduce or eliminate air-bone gaps. This may result in an abnormal, audiometrically induced bone-conduction threshold shift and suggest to the otologist the need for auditory brainstem response testing and/or magnetic resonance imaging. A case is presented in which the inappropriate use of the masking plateau method resulted in a reduction of the air-bone gap in an ear with a mild conductive hearing loss. The audiometric Weber test should be used in these cases, and nonmasked bone thresholds should be used to determine the actual level of the cochlear reserve.