Verification of the air-bone gap using cancellation and evoked responses

Using the cancellation method as well as evoked responses, we investigated their application in the estimation of the air-bone gap in patients undergoing operation on middle ear structures. The cancellation method had a closer relationship with pure-tone audiometry than evoked responses in predicting the air-bone gap. This was caused by recruitment, by which the cancellation method was not affected. The results of brainstem-evoked responses to bone and air conduction signals showed therefore an underestimation in the prediction of the air-bone gap. Combining the cancellation method with evoked responses elicited to air conduction signals permitted the estimation of the cochlear reserve without the need of threshold measurement by bone conduction.