Paul Langevin discovered that a water tank insonated with high-intensity ultrasound killed fish immediately, and certain observers experienced “a painful sensation on plunging the hand in this region."
P. Langevin: French Patent No. 505,703 (filed September 17, 1917; issued August 5, 1920) H. Freundlich, K. Söllner and F. Rogowski: Klin. Wochenschr. 11 (1932) 1512.