MIKE SPRINGER/Staff photo
Austin Monell, a junior at Gloucester High School, levitates three small pieces of styrofoam in mid air Monday using an acoustic levitator he built himself in the school's engineering department. Monell found instructions for making the device online, and he and classmate Aiden Cunha each made one under the supervision of engineering teacher Kurt Lichtenwald. The device uses about 70 miniature piezo speakers arrayed on opposite sides to create a standing soud wave. At each node, or place where the wave has minimum amplitude or air pressure, a tiny solid object or even a drop of liquid can be held aloft indefinitely. "It's a great demonstration of how sound moves in waves," said Monell.