Subjective Idiopathic Tinnitus-Review

Psycho-acoustical research is providing substantial advances in the understanding of Subjective Idiopathic Tinnitus (SIT). Tinnitus can be induced with loud noise. Haze11 (1977), presents an excellent review of this psychoacoustical research. Flottorp (1953) and Ward (1955) used a short stimulus tone followed by a silent interval, varying the intensity of the stimulus from threshold to 60 dB SPL.Subject listened for aftertones and/or beats (during the silent period). The after tones were called idio-tones, and often coincided with a localized area of hearing loss. Salmivalli (1967) described the instance of tinnitus after gunfire in army personnel. Loeb and Smith (1967) and Hempstock and Atherley (1970) used bursts of sound of one-third octave bands of noise at 110 db. for five minutes and produced a noise induced short duration tinnitus.

The temporary threshold shift showed a good relationship between the frequency of the maximum threshold shift and the frequency of the inducing stimulus. Wegel (1928) observed that pure tones ‘beat’ against his own tinnitus. Ward and Martin (1976), in investigating the relationship of pure tone tinnitus to a pure tone audiogram, showed peaks of increased sensitivity to coincide with the frequency of the pure tone tinnitus. Psycho-acoustical measurement of established tinnitus is necessary. Fowler (1938) measured tinnitus by a loudness balance procedure. Mortimer (1940) used a variable frequency source to measure the pitch of tinnitus in a free field sound-treated room. Goodhill (1952) used a list of 27 different sounds which constituted a tinnitus identification test. A ‘matching’ system is necessary in patients with SIT. The tinnitus synthesizer is an instrument which is of value in this regard. This allows identification of the tinnitus. Reed (1960), Graham and Newby (1962) and Nodar and Graham (1965), studied the acoustical characteristics using sweep frequency audiometers. They reported a higher pitch of tinnitus in patients with sensorineural hearing loss than conductive deafness except for a few cases of Meniere’s disease.