[Effect of intermittent noise on the function of concentration maintenance (TAF) and the brain waves (author's transl)].

The effect of three different kinds of noise, having equal physical energy but different psychological load, was examined by the TAF-test and the brain waves. Thirty nine healthy male subjects aging from 19 to 34 were exposed to white noise of 80 dB (C) under the following three conditions: (1) continuous noise for ten minutes, (2) regular intermittent noise, consisted of one-minute noise and one-minute rest, for 19 minutes, and (3) irregular intermittent noise, consisted of one-minute noise and irregular rest period, for 19 minutes. In each condition, the duration of noise-exposure totals ten minutes. Before, during and after the noise-exposure, the TAF-test was given to the 23 subjects out of 39, and the brain waves were recorded from the rest 16 subjects. The changes of TAF-L and alpha wave appearance were compared. The results obtained were as follows. 1. All three kinds of noise-exposure caused significant lowering of the function of concentration maintenance, especially in the latter half period of the noise administration. 2 Lowering of the function of concentration maintenance due to the irregular intermittent noise-exposure was greater than that due to the regular intermittent noise-exposure. 3. As to the continuous noise-exposure, appearance of the alpha wave decreased significantly in the 9th to 10th minute of noise administration and in the 1st min. after the exposure, while it increased in the 18th to 22nd min. after the exposure. 4. Exposure to the regular intermittent noise resulted in a significant decrease of the alpha wave appearance at the latter half of the noise administration, which continued after the exposure. 5. Exposure to the irregular intermittent noise caused a significant decrease of the alpha wave appearance after the middle period of noise administration. 6. Comparing the regular intermittent noise and irregular one, the latter brought about stronger alpha-blocking during the noise administration, but earlier restoration after the exposure. These results indicate that the influences of noise as a stressor differ not only by the amount of its physical energy but also by the condition of its generation, and that the differences of on-off effect on the brain activities based on regular or irregular intermittent noise were grasped by the changes of the function of concentration maintenance and the alpha wave appearance.