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ENERGY FROM SOUND
Yes, electricity can be generated (directly) from sound energy. The process, however, can't be "scaled up" for power generation. But for other applications, it is superb. Electricity can be generated directly from sound energy by piezoelectric effect. The way it works is that the mechanical energy of sound is applied directly to a crystal (or possibly a ceramic) with strong piezoelectric characteristics, and the crystal will generate a small amount of voltage in response to the application of that mechanical energy (sound). What we are doing is "squeezing" the crystal. A squeeze will generate a small voltage for the duration of the squeeze. When the crystal is released, another small voltage will be generated in the opposite polarity. We use the idea all the time when we use ultrasound in medical and other imaging. The military units of the Navy use it widely in sonar applications, and there are broadly demonstrated uses of marine sonar as can be seen on many video productions of marine exploration, discovery and salvage operations. As stated, the piezoelectric conversion of mechanical energy (sound) directly to electricity is something we can only do on a small scale. But it is exceptionally useful that we can apply the technology to imaging and testing as well as to the marine sonar applications that we have come to know.