STUDY ON THE PITCH OF TINNITUS WITH A SYNTHESIZER

Abstract

The results of pitch match test with a synthesizer (DANAC 100) were reported in this study. The pitch match test was perfomed in 60 tinnitus ears and the discrimination of five kinds of test tones produced from the synthesizer was examined in 6 normal hearing subjects. The short-term reproducibility of the results of pitch match test with the synthesizer was also studied in 10 tinnitus ears.
The results were as follows:
1) Seventy-five percent of tinnitus was simulated with sine waves.
2) The incidence of tinnitus simulated with sine waves was high in high-pitched tinnitus. In contrast, the pitch of tinnitus simulated with clipped sine wave and square wave was existed only in low frequency.
3) There was no clear relationship between the onomatopoetic expression of tinnitus and the test tones of the synthesizer.
4) Most of the tinnitus simulated with pure tones of the pure tone audiometer were simulated with sine waves of the synthesizer, and the tinnitus simulated with band noise and white noise of the pure tone audiometer were simulated with test tones other than sine waves of the synthesizer. When the pitch evaluated from 0.1 octave step test with the synthesizer was compared with that in 1.0 octave step test with the pure tone audiometer, an aberration to the higher or lower frequencies was found evenly in any frequency area. However, the degree of their aberration was mostly less than one octave.
5) A consistency of the pitch evaluated from 0.1 octave step test between contralateral and ipsilateral evaluations was found in only 17.3% of the subjects. Other tinnitus showed an aberration of the pitch to the higher or lower frequencies evenly in any frequency area, and the degree of their aberration was more than 0.1 octave. In 86.5% of the subjects, there was no difference of test tones of the synthesizer using for the simulation between contralateral and ipsilateral evaluations. Most of these tinnitus were simulated with sine waves. A consistency of test tones of the synthesizer using for the simulation between contralateral and ipsilateral evaluations was poor in the tinnitus simulated with test tones other than sine waves, and a large aberration of the pitch was also found in these tinnitus.
6) When the discrimination of five kinds of test tones of the synthesizer was examined in 6 normal hearing subjects, it was difficult to discriminate four kinds of test tones except pulse waves in high frequency. Also a big difference of discrimination rate was found in high frequency when an order of presenting two test tones was reversed.
7) As far as the short-term reproducibility of the results of pitch match test with the synthesizer was concerned, only 50% of tinnitus showed the excellent reproducibility of the pitch and the test tones using for the simulation, and they were simulated with sine waves.