抄録
Many workers began to complain of dim hearing in an iron factory eight months after their employment. The factory was found to be in noisy circumstances of about115-135 phons.
The audiometric examinations were exercised onthose 13 workers and the other 50 who had worked in the other branches of the factory.
The intensity of the noise was 115dB SPL lmeter away from the noise source, and 105 dB SPL 10 meters away. The distribution pattern of the noise frequency had a peak in mid frequency range.
The pure-tone audiograms of these 13 workers showed bilateral symmetrical hearing. 10ss in all frequencies, and the audiograms of the other 50 workers showed a typical high-frequency hearing-loss. Some differences were observed in the grade of hearing-loss of these 13 cases, although they were employed on the same day. Three cases had 20-30 dB hearing-loss, five cases 40-50 dB, and four cases above 60 dB.
It was presumed that the intense noise for several monthes had caused such afull-frequency hearing-loss.
