Process and Emergence on the Effects of Infrasonic and Low Frequency Noise on Inhabitants

Abstract

To clarify the process and emergence of the effects of infrasonic noise on man, the sound pressure level of infrasonic noise was measured in the area along a superhighway, and its effect on the inhabitants was investigated by the questionnaire method. The results are as follows: (1) The main component frequency of the infrasonic noise was 6.3 Hz. The sound pressure level (L50) of infrasonic noise (1–50 Hz) showed more than 85 dB in the daytime and more than 72 dB in the night time. It's peak level was above 100 dB under the overhead bridge of the superhighway. Indoors, the sound pressure level (L5) of infrasonic noise often went above 75 dB. (2) Answers about the living environment were given by 368 (85.6%) out of 430 families. Those about the condition of health were given by 909 cases (81.7%) out of 1113 cases who were all the inhabitants over 15 years of age. (3) 69.6% of families complained of the shaking of windows and the like. 65.8% of families complained of window rattling. More families complained of the shaking and rattling of windows in the area less than 80m distant from the superhighway, and more families also complained of the disturbance of sleep in that area. (4) The rates of the complaints as to ‘irritating’, have headaches', ‘head feels heavy’, ‘pain in arms or legs’, ‘feel languid’, ‘sleepless’, ‘dizziness’, ‘ringing in the ear’, and ‘difficulty in breathing’, were correlated with the distance from the superhighway. While the rate of complaints as to ‘have stiffness or pain on shoulders’ was highest, it had no relationship with the distance from the superhighway. From these results, it can be concluded that the inhabitants first complained of the shaking and rattling of windows by infrasonic noise, and then became chronically insomniac and excessively wearied by shaking and rattling of long continuance, and finally became highly sensitive to infrasonic noise. This increasing sensitivity might be closely connected with the emergence of the effect of infrasonic noise upon these inhabitants.