In recent years, a demand for the early diagnosis of the occupational deafness, the streptomycindeafness and the deafness in school children has been increased.Since these deafness have characteristic types on the audiograms respectively, the followingmethod of the screening test was performed and found- to be very excellent, being more simpleand easier compared with the ordinary audiometry.1) Prefessional deafness: One thousand one hundred and tmenty-eight ears were examined usinga pure tone of 4000 cps at 30db. The screening errorwas 1.55% and 1.91% in each side.2) Streptomycin deafness: One thousand and forty-five persons were examined using a pure toneof 8000 cps at 15db. without error. It was found in this case that the test of one ear was sufficientto screen the streptomycin deafness.3) School children deafness: Five thousand three hundred and eighty-two ears were examinedusing two pure tones of 1000 and 4000 cps at 20 db. respectively. In each case, the reason whyabove mentioned value of cps and intensity used in the test was discussed and results werecompared with that of the audiometry
Based on clinical and immunological studies, we have proposed the hypothesis that occupational dust exposure might cause not only pneumoconiosis but also autoimmune diseases and malignancies of various organs such as neoplasms of lymphatic and hematopoietic tissues and gastric cancer. Evidence from cohort studies of pneumoconiotic patients in Japan, copper miners, and stone masons support our hypothesis. The carcinogenicity and cytotoxic effect of inhaled dust on immune cells are considered to contribute to the development of these diseases.
An interrnpted tone (on-fraction 0.5; tonal duration 2000 msec; 3000 cps, 95 db (SPL)) was applied to induce TTS for 10 normal ears.The relation between the total duration of the interrupted stimuli and the degree of TTS was studied for both ATP-applied group and non-applied group (Fig. 1).From these results it was found that ATP was effective to reduce the degree of TTS, and the recovery time from it.Authors studied also on the intraauralmusle reflex and on the intensity duration threshold.Considering these results, they concluded that the preventing mechanism of ATP from TTS was due to the process of time constant elamant in perceptional mechanism.
The authors reported a case of reduced bone conduction threshold in a middle freqency range following chronic adhesive otitis. After preparating the ear drum from the promontorium and removal of the granulation around the ossicles, bone conduction threshold improved about 15db at 3000Hz., 4000Hz, and 5000Hz. From such findings the authors felt that the bone conduction threshold in a middle or high frequency range was not always considered to suggest a degree of impairment of perceptive organ. In this case the granulation around the ossicles and the adhesion of ear drum may be considered as contrib- uting to the mechanism of bone conduction improved about 15db in a middle or high frequency range. llighrly.
