NEUROPHYSIOLOGICAL MODEL OF TINNITUS - DEPENDENCE OF THE MINIMAL MASKING LEVEL ON TREATMENT OUTCOME

Validity of the neurophysiological model of tinnitus (Jastreboff, 1990 ), outlined in this paper, was tested on data from multicenter trial o f tinnitus masking (Hazell et al., 1985). Minimal masking level, inten sity match of tinnitus, and the threshold of hearing have been evaluat ed on a total of 382 patients before and after 6 months of treatment w ith maskers, hearing aids, or combination devices. The data has been d ivided into categories depending on treatment outcome and type of appr oach used. Results of analysis revealed that: i) the psychoacoustical description of tinnitus does not possess a predictive value for the ou tcome of the treatment; ii) minimal masking level changed significantl y depending on the treatment outcome, decreasing on average by 5.3 dB in patients reporting improvement, and increasing by 4.9 dB in those w hose tinnitus remained the same or worsened; iii) 73.9% of patients re porting improvement had their minimal masking level decreased as compa red with 50.5% for patients not showing improvement, which is at the l evel of random change; iv) the type of device used has no significant impact on the treatment outcome and minimal masking level change; v) i ntensity match and threshold of hearing did not exhibit any significan t changes which can be related to treatment outcome. These results are fully consistent with the neurophysiological interpretation of mechan isms involved in the phenomenon of tinnitus and its alleviation.