103 Development of a transportable device generating an infrasound : Active noise control of infrasound by using the low frequency sound source

Two devices generating an infrasound used for field experiments were developed. The first one can generate continuous infrasound with a pressure level over 110 dB at a distance of 3 meters within the frequency range of 5 -20 Hz. This device is transportable using a truck. The other one generates infrasound over 100 dB within the same frequency range. This device is mounted in the van and is more transportable than the former. We conducted field experiments using both devices to verify active control technology for infrasound. The experiments results indicated that this method could reduce infrasound of 5 Hz by over 25 dB.