Tone Decay in VIIIth Nerve and Cochlear Lesions

Abstract

A tone decay test was given 18 subjects with VIIIth nerve lesions, 53 subjects with Meniere''s disease, and 28 subjects with other cochlear lesions. The test incorporated 20-second rests between 5 dB [decibel] increments in tone presentation. The three dimensions of decay, the number of frequencies showing decay, threshold levels, and changes in rapidity differentiated VIIIth nerve and cochlear lesions. VHIth nerve subjects characteristically decayed at all frequencies showing hearing loss. About 60% of the Meniere''s group showed no tone decay or decay at only one or two frequencies, 40% showing decay at several or all. Results for the Meniere''s and cochlear groups are essentially the same.