1981 Volume 135 Issue 2 Pages 179-186
YAMAMURA, K., MAEHARA, N., HARABUCHI, I., SADAMOTO, T., TAKAHASHI, K. and HAYAFUJI, C. The Effects of Intermittent (Trapezoidal) Noise on Man. Tohoku J. exp. Med., 1981, 135 (2) 179-186-Eight healthy students were exposed to intermittent noise to evaluate the effects of traffic noise on man. The experimental noise exposure conditions were as follows: Exp. 1: Control. Exp. 2: Peak level, 80 dB(A); rise-decay time, 1sec; duration, 3sec; and duty cycle 8sec (on fraction 25%). Exp. 3: Peak level, 75 dB (A); rise-decay time, 500msec; duration, 4.5sec; and duty cycle, 8sec (on fraction 50%). In all experiments, the exposure time was 14hr. Temporary threshold shift (TTS) growth was followed for 14hr while saliva cortisol levels were measured for a 24-hr period. Although the coefficient of the regression line of TTS growth recorded in Exp. 1 or Exp. 3 was not statistically significant, the value in Exp. 2 was statistically significant. The circadian rhythm pattern of the saliva cortisol level (during a 24-hr period, mean of 8 examinees) was observed in the three experiments. Essentially, the early morning level of saliva cortisol was high, while the daytime level was relatively low.
