Abstract
Hearing changes in seven frequencies (125 to 8000Hz) in air conduction threshold were studied at one month and at six months after tympanoplastic surgery in 863 ears. The hearing improvement in ears that received type I tympanoplasty with good ventilation in the epitympanic space was greater in the low frequencies than in the middle frequencies. The rate of improvement in the low frequencies was nearly 100% at one month after surgery. Increased threshold was observed at 8000Hz in ears that received type I tympanoplasty with or without good ventilation in the epitympanic space. This increment, however, had disappeared by the six months' hearing test. The cause of this transient increment in the hearing threshold at 8000Hz was probably due to impedance changes in the middle ear caused by surgery. Threshold changes with modified type III and modified type IV tympanoplasty were similar. That is, threshold improvement at the low and middle frequencies was of the same degree and no transient increment at 8000Hz was observed.
