Human whole-body exposure to infrasound

Four male subjects were exposed to infrasound ranging from 1 through 20 Hz for a period of 8 min up to levels of 144 dB re 20 micropascal. There was no objective evidence (including audiograms) of any detrimental effect due to infrasound; however all subjects experienced painless "pressure build-up" in the middle ear that was relieved by valsalva maneuver or by cessation of infrasound, and voice modulation and body vibration consistently occurred. It is concluded that infrasound exposures as high as 144 dB are safe for healthy subjects, at least for periods of 8 min, and it is predicted that longer exposures will also be safe.