Vibratory Sensation Induced by Low-Frequency Noise: A Pilot Study on the Threshold Level

The induction of vibratory sensation is a characteristic of low-frequency noise. In this pilot study we measured the threshold levels to induce a vibratory sensation in normal-hearing subjects exposed to pure tones within a narrow frequency range (20-50 Hz). The threshold levels necessary to induce a vibratory sensation were found to be 5-17 dB(SPL) higher than the hearing threshold levels; these vibratory sensation levels were lower than the sensation threshold levels in deaf subjects previously measured by another research group. This difference suggested the possibility that the function of the hearing organs is related to the perception of vibration in normal-hearing persons exposed to low-frequency noise. Our study showed that the head was the part of the body in which the vibratory sensation was most often experienced, which supported the idea that the hearing organs may contribute to the normal-hearing person's perception of vibratory sensation. Another interesting finding of our study was a dip appearing in the threshold level for the vibratory sensation at 40 Hz. This was broadly in agreement with another group's result that sensitivity to vibration was greatest at frequencies between 40 and 80 Hz.