Kankakee Valley Post, Volume 19, Number 6, DeMotte, Jasper County, 7 January 1949 — It's a Sound Idea [ARTICLE+ILLUSTRATION]

It's a Sound Idea

From the tweezers he holds, General Electric engineer George Ledges, Schenectady, N. Y., dropped 11 pieces of cork and they remained suspended in mid-air. The fragments are held aloft by sound waves, pitched too high to be heard by the human ear. Waves, from a tiny air whistle two feet above the tweezers, are focused on the metal reflector at bottom. The waves coming down meet those coming up, creating a still area where the cork remains stationary.