Tympanometry is well established as a useful tool in the field of otological diagnosis. There have been sporadic reports, however, of bizarre tympanograms in the presence of small perforations of the tympanic membrane. A model of the outer and middle ears was fabricated which was able to produce normal and pathological tympanograms. This model was used to investigate tympanometry in the presence of microperforations. A hypothesis for the mechanism of generation of sawtooth tympanograms in the presence of micro-perforations is postulated.

Neurofibromatosis type 2 (NF2) causes bilateral hearing loss due to tumour growth in the cerebellopontine angle. We report the results of promontory testing and transtympanic electrocochleography on subjects with deafness due to NF2 referred for an auditory brainstem implant. All 19 ears tested revealed loss of cochlear microphonics. Nine ears (mainly without previous treatment) revealed auditory perception during promontory stimulation, indicating cochlear deafness. One of these subjects has been successfully provided with a cochlear implant. The other 10 ears (mainly after previous surgery) revealed negative promontory stimulation, indicating additional retrocochlear deafness. These findings indicate that neurofibromas initially cause a cochlear deafness, so that a cochlear implant can be used if the auditory nerve can be preserved. This option has to be considered in rehabilitating patients with bilateral tumours due to NF2.

Hearing impairment can be the cause of significant disability and handicap. This medico-legal case demonstrates the need for accurate assessment of both the severity and type of hearing loss if the best clinical management is to be provided. In particular, the case identifies the critical role of additional, objective auditory testing when pure tone audiometry, which depends on the subjective response of the individual, is inconsistent or indicates severe hearing impairment.

Extratympanic electrocochleography (ECochG) was performed on 37 patients referred to the Evoked Potential Clinic with suspected Ménière's disease. The patients were classified according to their hearing impairment and audiometric configuration. Click and tone-pip stimuli with tone frequencies of 1 and 4 kHz were presented at a rate of 10 per second. Amplitude, latency and general waveform characteristics of the summation potential (SP) and action potential (AP) were analysed for each averaged response with respect to the level and configuration of the hearing loss. The highest incidence of abnormal percentage SP was in patients with average hearing loss in the range of 40–64 dB HL using the click stimulus. In low tone hearing loss, hydrops was identified from an enhanced SP in significantly more patients using the click and 4 kHz tone-pip than the 1 kHz stimulus. Measurement of the width of the 1 kHz tone-pip response waveform was abnormal in some patients even though the click and 4 kHz responses were normal. The optimum stimulus for identification of hydrops from an enhanced SP is dependent on the level and configuration of the hearing loss.

A prospective study of the effect of radiotherapy for nasopharyngeal carcinoma on hearing was carried out on 49 patients who had pure tone, impedance audiometry and auditory brain stem evoked response (ABR) recordings before, immediately, three, six and 12 months after radiotherapy. Fourteen patients complained of intermittent tinnitus after radiotherapy. We found that 11 initially normal ears of nine patients developed a middle ear effusion, three to six months after radiotherapy. There was mixed sensorineural and conductive hearing impairment after radiotherapy. Persistent impairment of ABR was detected immediately after completion of radiotherapy. The waves I–III and I–V interpeak latency intervals were significantly prolonged one year after radiotherapy. The study shows that radiotherapy for nasopharyngeal carcinoma impairs hearing by acting on the middle ear, the cochlea and the brain stem auditory pathway.