> It seems that the unit with the unusual size of 160 cm had a lot of difficulty in the characteristic test. At the Koriyama Test at the Koriyama Factory was carried out in the measurement room at first, but it was stopped because fluorescent lamps on the ceiling fell due to vibration. It seems that the characteristic test was carried out at the ground in the factory premises.

> The outdoor test seemed to have a negative impact on the neighborhood. At a distance of about 100m from the speaker, it was felt as sound, but at a distance of more than that, it was transmitted as vibration and earth rumbling instead of audible sound. Within a radius of 2 km from the factory, there were damages such as vibrations like earthquakes and earth rumbling, and sound of walls and windows.