[Clinical study of noise-induced deafness. Part 12: Results of tests on cases of tinnitus and evaluation].

For 80 cases of noise-induced deafness, various tests on tinnitus were performed to obtain results as follows. 1) When tinnitus was analyzed by the tinnitus questionnaire, many had bilateral tinnitus all the time, while few noted changes in the tone and loudness of sound. 2) As for the tinnitus frequency obtained by the pitch match test, cases with 4 kHz or more were many, accounting for 81 percent. The average tinnitus frequency was 5500 Hz. The rate of agreement with the frequency for the maximum hearing loss was 55 percent. In cases where the tinnitus frequency was not in agreement with the frequency for the maximum hearing loss, the tinnitus frequency was noted in the lower range of tone than the frequency for the maximum hearing loss. 3) The loudness of tinnitus is measured by the loudness balance test was not more than 5 dB in 86 percent of the cases. 4) As for evaluation on the subjective expression, expressions such as "zee", "keen", "meen" were many. On the pitch-match test, most of tinnitus was of the pure tone but there might be some composed of noise judging from onomatopoeic words. As for evaluation, the subjective expression was considered close to the tinnitus frequency when emphasis is placed on 2 points of evaluation. 5) As for results of the masking test, convergence type and distance type according to the Feldmann's classification were found in many cases. 6) When the tinnitogram was classified into 5 types, the high-pitched tone obliquely dip type and the dip type accounted for 80 percent. The masking inability was noted in 9 percent. The agreement between the lowest frequency for masking in the masked cases and the tinnitus frequency in the pitch-match test was found in 82%, if similar cases are included. This shows that the tinnitus frequency can be found from the masking test as well. 7) A look at the masking level at each frequency indicated that the band noise at 125 Hz might be a sound that can be masked regardless of the tinnitus frequency. 8) The rate of RI appearance was low at 36 percent, indicating that the white noise 80 dB failed to mask tinnitus.