This is the Mitsubishi Dialtone D160, the largest 60-inch subwoofer ever made in the 1980s. Weighing in at 800kg, it can easily shatter windows and generate small earthquakes that can be felt as ground vibrations within a 2km radius. At the Koriyama plant, the test was initially conducted in a measuring room, but was stopped because ceiling lights fell due to vibrations. The outdoor test apparently had a negative impact on the neighborhood. At a distance of about 100m from the subwoofer, the sound was noticeable, but at greater distances it was transmitted to the ground as vibration and noise rather than as audible sound. Damage such as vibrations, small earthquakes, and noise from walls and windows occurred within a 2km radius of the plant.