電話交換手の難聴に関する研究

抄録

Hearing test were performed on, 115 telephone operators in 1956, 134 operators in 1957, 133 operators in 1958 at Aomori Telephone Exchange Office, and on 116 operatiors in 1948 at Hirosaki Telephone Exchange Office. Following conclusion was obtained.
(1) Appearance of hearing disorders were found in 10.9%, 14.2%, 17.7%, and 22.4% respectively and in over 80% of them it was perceptive nature. Moreover, about 50% of the perceptive deafn-ess, they seemed to be hearing disorder caused by the use of recerver.
(2) About the hearing disorder due to the use of receiver, the following results were obtained.
a) More than 90% of them, hearing disorder was slight, being less than 30db hearing loss in average.
b) The incidence was remarkable in males, who had been working oner 5 years.
c) Among the operators who had been working less than 5 years, author could not find the cases, whose hearing loss average was morethan 30db. In most of them, it was less than 10db hearing loss in average.
d) About the shapes of audisgram, author found dip-form most frequently, and next (in order of) V-form, U-form and gradual sloping-form. The dip was found in c4 most frequently.
e) In the cases who h-ad been using receiver on one ear only for listening, the incidence of deaf-ness was higher than in the cases who had beenusedon ears alter natively.
f) During 2 years' observation, an increase of hearing loss especiall in 2000cps at 500, 1000, 2000, 4000cps was found. But there were no cases showing improvement or progression over 15db in average of 4 frequencies.
g) As the result of the detailed examination, more than 70% of cases were showed positive Onchi and DL test. In the test of the speach articulation by conversation rate, more than half of the mild eases showed slight hearing disorder at 40db of the speach sound power. In 3 cases with moderate orsevere grade hearing loss, the disorder was observed at even 90db.
(3) Hearing disorder of the telephone operators has the characteristics that it frequently shows the audiogram of C4-Dip. It is the authors conclusion that these facts are due to that most sound is around 1000cps, and the energy sometimes exceeds the limit of sound criterion.