Tinnitus as a source of internal noise

Abstract

For 7 patients with sensorineural hearing loss and tinnitus, pitch and loudness matches were made to the tinnitus. These matches were followed by measurement of three psychometric functions (probability of a correct response as a function of signal level) for pure tones, one in the presumed tinnitus region (i.e., at the average frequency matching the pitch of the tinnitus), one below the minimum frequency of the matches, and one above the maximum frequency of the matches. The data reveal that pitch-loudness matches are usually quite variable and that the slope of the psychometric function is flattest in the presumed tinnitus region. The first result is consistent with the idea that tinnitus is an unstable signal. The second result is consistent with the notion that the unstable tinnitus acts as a source of "internal" noise.