Calculation of hearing results after tympanoplasty.

At present there is no universally accepted method for calculating hearing results after chronic ear surgery. In this study the methods most frequently used have been applied to a material of 105 tympanoplasties and compared to each other. In addition a comparison between pre- and post-operative bone conductions (BC) thresholds for calculating post-operative air-bone gaps has been performed using multiple regression analysis. The results lend support to the conclusion that BC thresholds will improve with surgery in successful cases and that the post-operative BC threshold is a closer approximation of the cochlear function than the pre-operative one and consequently should be used for gap calculations. However, until the masking procedures in audiometry are standardized, hearing gain may be regarded as the most satisfactory alternative for describing hearing results as it is based on the air conduction thresholds only. This method requires a careful description of pre-operative air and bone conduction thresholds.