Discrimination of level differences by hearing-impaired patients.

A technique for measuring the discrimination of level differences with pulsed tones is proposed. Alternating tone bursts, each of 500 ms duration but of different sound pressure levels, are separated by 200-ms pauses. The advantages of this method in comparison with traditional methods (SISI test, Lüscher-Zwislocki test) which use modulated tones are that level discrimination is independent of frequency and that it shows very little dependence on sensation level. With this technique, the level discrimination of patients with conductive hearing loss, 'toxic' hearing impairment, noise-induced hearing loss, sudden deafness, presbyacusis, Meniere's disease, and retrocochlear impairment was determined and compared to the results obtained in normal ears. Using the level discrimination test proposed, retrocochlear disorders can be diagnosed with great reliability.