Abstract
In many working environments the total noise energy is dominated by infrasonic frequencies. Exposure to this type of low frequency noise has, by several authors, been correlated to different effects on human subjects. Recent laboratory experiments have thus indicated correlations between noise, perception and other effects on humans. Exposure to infrasound therefore appears to become a hygienic problem when the pressure level exceeds the threshold of perception.
The present paper is a description of various laboratory experiments on perception and the physiological effects of infrasound. Subjects were exposed to pure tones and broad-band noise within the infrasonic range. Changes in perception, and physiological reactions, during different types of exposure are described. The paper also includes levels and frequency analyses of noise emanating from some of the most common infrasonic sources: buses, lorries, trains, railbuses, ships, helicopters, manoeuvre rooms and mills. The characteristics of the noise spectra are compared and related to the threshold of perception. Finally, field studies on physiological changes correlated to wakefulness in typical and authentic infrasonic noise environments are described.
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