The relationship between the contralateral hearing threshold in the operated ear and the type of tympanoplasty and the hearing threshold in the operated ear was investigated in this report. The subjects of analysis were 863 ears that received tympanoplasty during the past nine years at the Nippon Medical School Main Hospital. Patients who had good hearing in the contralateral ear received type I tympanoplasty more frequently than did those who had poor hearing on the contralateral ear. On the other hand, patients who had poor hearing in the contralateral ear received a modified type III tympanoplasty more frequently. Patients who had good hearing in the contralateral ear tended to have better hearing in the operated ear compared to those who had poor hearing in the contralateral ear. The hearing threshold in patients who had normal contralateral hearing on the average had 20 dB better hearing than did those who had profound hearing loss in the contralateral ear. More than one third of the patients whose hearing thresholds were worse than 30 dB in the operated ear also had a contralateral hearing loss of 30 dB or more. The decision to perform tympanoplasty in cases of the better hearing ear or the only hearing ear must be made very carefully. The contralateral hearing in patients with chronic otitis media, however, is frequently not normal as was evidenced in this investigation. Also, patients who had poor hearing or were deaf in the contralateral ear received more benefit by tympanoplasty than did those who had good hearing in the contralateral ear. Thus, the otologic surgeon should improve his techniques to cope with difficult cases, such as the better hearing ear and the only hearing ear.
