Abstract
This paper presents a discussion of perception mechanism for infra, low frequency sound (ILFS), which radiated from industrial machines and facilities, and large structures. Now the permissible sound pressure level on health in the range from Infrasound frequency to audible frequency is discussed in European countries. But these recommended permissible SPL applied in this frequency range, which is based on the experimental data of laboratory may be unsuitable for the estimation of the effect of ILFS on health in the infrasound frequency rang, especially below about 10Hz. Approximately on the frequency range above 10Hz, Polish recommendation as A10 will be suitable in actuality as shown in Fig.3. Then, a perception mechanism of infrasound, which may be imperceptible physiologically as sound is viewed from the physiological perception mechanism, the bio-mechanism of perception is not controlled by the magnitude of physical stimulus, and is almost controlled by sensing the instantaneous change of stimulus. A necessity of a dynamic estimation of sound pressure level and sound frequency spectrum as a function of time is discussed.
