An Infrasound Experiment System for Industrial Hygiene.

An infrasound experiment system has been constructed in order to investigate the effects of infrasound on human health from the point of view of industrial hygiene and to establish a method to assess it in working environments. Some measurements were carried out to evaluate the acoustic performance of the system in the low frequency sound range, including infrasound, and to clarify the points to be improved. As a result, it was found that the system had some weak points in the audible frequency range. They were considered to be caused by the large capacity of the test chamber, and some countermeasures were required. On the other hand, in the infrasound range, it appeared that the higher harmonics of infrasound possibly affected the experiments and some limitations might be found necessary. But the frequency response of the chamber and the spatial uniformity of the reproduced infrasound proved to be satisfactory for the experiments in this range. Consequently it was concluded that the system could contribute to the study of infrasound.