抄録
It is well known that the occupational hearing loss has very often occurred in the shipyard. Although factors contributing to the occupational hearing loss show a tendency to decrease according to the recent progress of tenchnology, it is reported that young workers in the shipyard having a seght hearing loss show a tendency to increase. It is presumed that this is related to the damage due especially to listening to stereophonic phonograph records in their daily life. Acoustic instruments such as stereophonic phonograph records, radio-cassette recorders, video recorders, and headphones for such acoustic instruments are easily available for daily convenience. They are playing important parts as factors of the daily sound environment. Measured sound levels to which young age groups were exposed in listening to the stereophonic phonograph records were 61 to 78 dB (A) in the case of Japanese songs and 63 to 98 dB (A) in the case of rock and roll music. Hearing losses were measured and the habits of such audiophiles were investigated among 382 workers in a shipyard from March to September in 1977. The results were as follows: 1) The percentage of the audiophiles is 48.6% of the sample subjects. And the younger the age group, the higher this percentage. 2) Difference of the average hearing loss by age group is significant at 1% level. This means that the natural loss of hearing exists as a result of aging. 3) Most of the audiophiles belong to the young age groups, and the average hearing loss of the audiophiles is less than of the non-audiophiles. 4) The average hearing loss of the audiophiles in twenties is less than that of the non-audiophiles in the same age group. 5) Average hearing losses classified both by listening durations and by kinds of chief listening music are not different at 5% level of significance. 6) The relation between the average hearing loss of the audiophiles and the duration of listening to stereophonic phonograph records is not significant. However, the relation between the average hearing loss and the listening frequencies is significant at 1% level. 7) 14.5% of the audiophiles are using headphones. The relation between the average hearing loss and the use of headphones is not significant. From the above facts, the authors consider that hearing loss of the younger age group has not been influenced by the sounds from sterephonic phonograph records under the present state. However, we have to pay attention to acoustic instruments generating sounds in the daily environment. Note: The average hearing loss is expressed in (a+2b+2c+d)/6, where a stands for threshold at 500Hz, b at 1, 000 Hz, c at 2, 000 Hz and d at 4, 000 Hz.
