A FAMILY with hereditary deafness is presented. The mother and ten of her children suffer sensorineural hearing loss. The maternal grandparents and four uncles and aunts were all hard of hearing. Clinical examination revealed no accompanying gross anomalies. In one child, Mondini deformity is the cause of deafness. In the rest of the family isolated membranous labyrinth deformity is suggested.

The methods of early diagnosis are discussed, among which polytomography proved the most reliable for diagnosing Mondini and Michel deformities. We demonstrated how early fitting of hearing aids is essential for language acquisition and speech development.

Clinical ability to differentiate between subtypes of inner ear hereditary deafness not accompanied by gross anomalies is limited. This problem and the problem arising from late diagnosis are illustrated by a report on a family of ten children, nine of whom suffer sensorineural hearing loss.

70 Patients with dry central perforations have been studied to assess the hearing loss. The hearing loss is greater at the lower frequencies and increases with the size of the perforation. Malleolar perforations cause more hearing loss than the non-malleolar unless the perforation involves less than 10 per cent of the tympanic membrance surface area. Perforations of the postero-inferior quadrant cause more hearing loss than those in the antero-inferior quadrant.

The large effective surgace area of an intact and normally vibrating tympanic membrane plays a major role in the middle ear transformer mechanism. The loss of this surface area by perforation is bound to cause deafness (Mawson, 1962). The degree of hearing loss has been extensively studied in human cadavers (Békésy, 1939) and in cats (Bordley and Hardy, 1937; Payne and Githler, 1951) but not much published work is available on any detailed clinical study in human beings. Most authors have generally stated that ‘small perforations’ have little effect on hearing, and only low tones are affected (Wever and Lawrence, 1954). In two individuals, Bordley and Hardy (1937) found average losses of 12 dB over frequencies ranging from 256 to 4,096 Hz. 10–30 dB loss is quoted by Simpson et al. (1967), and 20–45 dB loss in the speech frequencies by Thorburn (1971). It has been a general view that the hearing loss increases with the size of the perforation, more so it if is located in the postero-inferior quadrant (Mawson, 1962; Simpson et al., 1967; Thorburn, 1971). In a retrospective study of audiograms in 103 cases, Anthony and Harrison (1972) found that the maximum average loss occurred at 250 Hz., the loss being less in ‘small’ perforations (less than 2 mm. diameter) than in large ones, less in perforations touching the manubrium than in those away from it, and also less in perforations of the antero-inferior quadrant than in those in the postero-inferior quadrant.

The role regional flaps in the repair of oral defects is discussed and the flaps most commonly used described. An undelayed postero-lateral flap offers a useful alternative for the repair of ral defects.