Hearing results are presented for 164 ears with chronic otitis media which were operated on radically and obliterated with a musculo-periosteal flap (Palva flap), and in which tympanoplasty was performed. The ears were followed-up annualy for 5–13 years (mean 6.8 years). Results are compared with the method of ossiculoplasty and with the condition of the stapes superstructure at operation. Ossiculoplasty using autogenous cortical bone columellas resulted in a somewhat greater improvement in the post-operative air-bone gap than ossiculoplasty with auto- or homo-graft ossicles, when compared wih the pre-operative gap. Similarly, the post-operative gap improved more in ears with an intact stapes superstructure than in ears in which the stapes superstructure was absent. The use of an autogenous cortical bone columella can be recommended in cases in which the patient's own ossicles are affected by disease and cannot be used.

Hearing changes in patients treated with gentamicin have been prospectively investigated. A group of patients who had a similar spectrum of clinical conditions but did not receive gentamicin have been studied as a control group. The audiometric technique was first validated by recording audiograms from health volunteers, once in an anechoic chamber and twice in a ward. It was concluded that changes in threshold <20 db. should not be regarded as significant when measured in a ward.

In the gentamicin-treated group an initial audiogram was not a reliable measure of the patient's normal hearing because of the influence of their clinical condition. Twenty-one of the control patients were elective admissions to hospital and had their hearing first tested when they were clinically well. There was a 24 per cent incidence of unexplained hearing abnormalities—similar to the incidence of hearing loss in the gentamicin-treated group at follow-up. It was concluded that aminoglycoside auditory toxicity should not be assessed retrospectively.

The incidence of hearing changes in the control and gentamicin-treated groups were similar. Possible causes of hearing loss in surgical patients are discussed and recommendations are made for the conduct of future studies of drug-induced auditory toxicity.