Japanese researchers have developed a revolutionary type of glass that can show visually how loud a sound is and which direction it is coming from on a transparent display. Unlike ordinary sound measuring instruments, the Soundglass shows information on sounds emanating from the area that can be seen through the transparent display. Its applications include monitoring noise at electric power plants and other facilities to check for anomalies.

Safe and SoundThe Soundglass was unveiled in October 2009 by Chubu Electric Power Company, construction firm Kumagai Gumi, and Yamashita Yasuhiro, professor emeritus at Shinshu University. Malfunctions in equipment or instruments at power plants often cause abnormal noises, so detecting these sound anomalies is a vital element in maintaining the safety and efficiency of the facilities.
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The Soundglass device. (C)CHUBU Electric Power Co., Inc.
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Chubu Electric Power previously used ordinary sound measuring devices, but these pick up the sounds from 360 degrees around the point of measurement, making it hard to pinpoint where a specific sound is coming from. To overcome this difficulty, the firm teamed up with Kumagai Gumi and Professor Yamashita to develop a device that could visualize sound information and specify the direction of the sound source. In 2001, the NoiseCam, predecessor to the Soundglass, was completed.

The NoiseCam consisted of a sound-concentrating microphone and a digital camera. Images taken with the camera were combined with sound information including loudness, frequency, and direction and shown on a monitor. By visualizing the part of the images from where the sound was emitted it was possible to pinpoint the direction of the sound source. The sound-concentrating microphone consists of five microphones separated by several centimeters, and the direction of the sound source is specified by measuring and analyzing the lags between the times when the sound reaches each microphone. A circle centering on the direction from which the sound emanated is displayed on the monitor. The size of the circle indicates the loudness of the sound, so that the volume can also be understood visually. The frequency of the sound, meanwhile, is shown by the color of the circle, changing from red to blue with changes from high to low sound.