Abstract
Audiography using 4000 cycle was carried out to 490 coalminers. In 41% of the miners, slight hearing disturbance was observed. The percentages were difierent by the working position ranging from 60% to 35% and the continuity of the occupation was the longer, the rate of the incidence was the higher. Especially, in the cases continued the occupation for over 4 years, the fact was remarkable.
The audiogram of the cases was about 10db at 2,000 cycle and about 30db at 4,000 and 8,000 cycle.Hearing capacity of them in normal speaking area had not been disturbed.
