Effects of Infrasound on Involuntary Eye Movement during Fixation

Abstract

This study was undertaken in order to clarify the effects of infrasound on vestibular functions by comparing observations of eye movement under exposure to infrasound and audible noise. Twenty-five healthy males were exposed to a wide octave-band noise, (approx. 125 Hz to 4kHz) or to 16 Hz or 5 Hz at 95 dB for 3 minutes. Their involuntary eye movement with the eyes visually fixed in the horizontal direction was measured before and during exposure with their eyes open and closed. The extent of eye movement before the exposure was significantly greater with eyes closed than with eyes open. This difference was intensified by 5-Hz exposure, but exposure to the noise of 16-Hz infrasound had no effect. The power percentage in the low frequency-band, determined by spectral analysis of the eye movement, was significantly greater with eyes closed than with eyes open before the exposure. This increase in the power percentage in the low frequency-band was reinforced by the 16- and 5-Hz exposures, while no effect was observed upon exposure to the noise. These results suggest that the potential of the vestibulo-ocular reflex was increased upon exposure to infrasound, regardless of whether or not the subjects perceived any sensation.