A CONTRIBUTION OF THE SO-CALLED TELEPHONE DEAPNESS
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概要
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In order determine whether telephone deafness was caused by scoustio trauma or not, an efficiency of the telephones, auditory fatigue of the telephone operators and some conditions under which they were apt to suffer from telephone deafness were studied.The results obtained were as follow:1. The frequency ranges of the telephones were from 200 to 4000cps and the level of its sensitivity was 65db at 1000cps and its sensitivity: deviation between at 300cps and at 2500cps was only 10db. Therefore the sound pressure conducted to the ear of the operators was not over 70db.2. Of 914 telephone operators, 17.7% had hearing impairment.3. In the operators with normal hearing the level of auditory fatigue against one day work was within 15db and immunity from auditory fatigue was obtained with the increase of the years for which they worked. In operators who worked over 4 years the auditory fatigue was located in 500 to 2000cps. And in them who had worked over 8 years it was not recognized. On the other hand, in operators with telephone deafness it was from 15 to 30db.4. As the reuslts of the function tests, of the automatic nervons system, vagotonia was observed frequently in the apprentices and operators with normal hearing, followed by the operators with deafness. Especially the difference of its frequency between in the operators with normal and impaired hearing was remarkable. Sympatheticotonia, changeable vagotonia and non-reaction were obserevd frequently in them with deafness.5. As compaired with the operators with normal hearing, in the cases with deafness the irregular cellularityand absorption of the mastoid cells were more remarkable.6. By using Sawada's urinalysis method, the values of vitamin-B1 in blood were measured. Thirty percent of the cases with normal hearing and 62% of them with deafness were foued to be deficient in vitamin-B1.7. It is resonable to presume that telephone deafness is not caused by directors. As based on thase findings, it must be distinguished from usual occupational deafness.
- 一般社団法人 日本耳鼻咽喉科学会の論文