The noisy sound in Kanan (old type facilities) and Hokubu (new type facilities) country elevators, Izumo, were surveyed and the effect of noise prevention and the noise exposure time for worker were discussed.
The results were as follows;
(1) The predominant noise sources identified were the combustion furnace and the blowere for burning and drying on the heated-air drying system of both facilities.
As the combustion furnace in Hokubu was placed in the room partitioned off part of the building, the difference of the noise level between the inside and the outside of the room was 4-5 dB(A). It was very effective for the noise prevention. If both combustion furnace and blower for drying were partitioned off together, the noise level in the building would become lower.
(2) The noise level of the operator's room in Kanan was 79 dB(A) that was 8-10 dB (A) lower than the outside. In Hokubu, it was 67-69 dB(A), that was 13-15 dB(A) lower. From these results, the noise prevention by concrete wall was effective, as the operator's room in Hokubu was partitioned off with concrete wall.
(3) The permissible exposure time for operators working at near the predominant noise sources in Hokubu was above two times as long as that in Kanan on the basis of caluculation using the noise standerd permitted by both OSHA and the association of industrial helth of Japan.
(4) The noise levels at the boundary lines of both country elevators were from 59 to 68 dB(A) except the south side in Kanan. These levels were less than the noise standerd permitted as the industrial area (daytime) on the law of noise polution. But they had big problem when the drying of unhulled rice was worked in night-time.