Abstract
Thirty-four guinea pigs received infrasound (1, 10, 20 Hz) at 120-163 dB SPL for one hour. The animals showed no nystagmus and disturbance of balance during infrasound exposure. They were sacrificed fourteen days after the exposure. The cochleas were examined by means of a scanning electron microscope.
Pathological findings were hair cell damage and globus formation of the tectorial membrane in the apical turn of the cochlea. These morphological changes were observed in the ears exposed by 20 Hz at 163 dB SPL. No pathological changes were found in the tympanic membrane and the middle ear. As frequency and intensity of the sound increased the number of ears with pathologies increased. Globus formation was observed mainly at the marginal zone and the middle zone of the tectorial membrane. The authors consider that globus is a partial swelling of the marginal nets or an altered substance protruded from the inside of membrane tissue. The attachment of the sensory hairs to the undersurface of the tectorial membrane is disturbed by the globus formation. It is concluded from the present experiment that one hour exposure of the infrasound below 133 dB SPL does not induce any morphological changes in the guinea pig cochlea.
