The effects of variable noise level on man with peak levels below 75 dB(A).

To estimate the effect of variable traffic noise levels by field study, six healthy students were exposed to such noise for 8 h in a building beside a highway. TTS increases and blood pressure changes were observed. A summary of the results is as follows: 1. Noise level slightly exceeded 70 dB(A) (Equivalent Sound Level, Leq). The ninety percent range of the changing noise level was within L50 + 10 dB(A). 2. The Temporary Threshold Shift (TTS) induced by variable noise increased slightly in this field experiment. In particular, regression of the logarithm of exposure time (min) to TTS at the "S" ward office, was statistically significant. Some subjects showed a rise of blood pressure due to noise exposure. 4. Even though noise level is below 75 dB(A), 8 h noise exposure induces TTS increase and elevation of blood pressure.