Thirteen patients received stimulation of the cochlea using a transtympanic electrode. The purpose was to investigate the effect of alternating current on the normal and the damaged cochlea and also to discover what effect, if any, it has on tinnitus. Measurements were made of the electrical dynamic range and in one case a loudness balance test was performed against an acoustic signal in the contralateral ear. In addition nine patients experienced a variety of somatic sensations and four had vertigo. Tinnitus was temporarily suppressed in two out of nine cases.