The Threshold of Sensation for Infrasound

Abstract

Measuring apparatus was developed to examine the threshold of sensation for whole body exposure to infrasound in a closed chamber, in which pure tone and white noise were produced in the infrasound range. By use of this apparatus, the thresholds of sensation were measured for 62 subjects. The threshold for pure tones rises with decreasing frequency with a slope of −16 dB/octave above 10 Hz and – 2 dB/octave below 10 Hz. The threshold of sensation for white noise, converted into spectrum level, shows a similar pattern for all the subjects with slope of −19 dB/octave. Some subjects respond sensitively for pure tones below 10 Hz. It is suggested that they react in response to a sensation, such as a pressure sensation, other than the sense of hearing. It is also suggested that if those subjects were to become more sensitive, their thresholds of sensation would show similar patterns to those already reported in Japan.