A STUDY ON THE EFFECT OF INFRASOUND

Abstract

In order to examine the influence of infrasound that is becoming topical in society, human beings and guinea pigs were exposed to infrasound. After exposure, the hearing level, vestibular functions and autonomic nervous functions of human beings were examined, and endocochlear potential (EP) and cochlear microphonics (CM) of guinea pigs were examined. Next, after guinea pigs were exposed to intense audible low frequency sound that was born secondarily from infrasound and/or vibration of whole body concerning about air pressure change of infrasound, their EP and CM were examined.
The results obtained were as follows :
1) By exposure of infrasound 10-15Hz 130-135dB LSPL for 30min. to human beings, their hearing level, vestibular functions and autonomic nervous functions were not changed.
2) After exposure of infrasound 15Hz 135-140dB LSPL for 24hrs.-72hrs. to guinea pigs, their EP and CM remained normal.
3) After each exposure of audible low frequency sound 90Hz 120dB SPL for 72hrs., 150Hz 110dB SPL for 72hrs. and 200Hz 100dB SPL for 72hrs. to guinea pigs, their EP became abnormal though their CM remained normal.
4) After exposure of 15Hz 500-30 vibration for 72hrs. to guinea pigs, both EP and CM remained normal.
5) After exposure of both audible low frequency sound 150Hz 100dB SPL and vibration 15Hz 500-30 for 72hrs. to guinea pigs, their EP became abnormal though their CM remained normal.