Schallabstrahlung von Platten bei punktförmiger Anregung

An infinitely wide plate, set into damped flexural vibrations, radiates no sound energy if the wave-lengths in the plate are smaller than those in the air. If the plate is excited at a point, then the exponentially decaying “flexural wave near field” gives a small finite radiation, whose value is calculated. It is shown that the same relation holds for damped plates of finite size, but if the damping is small the radiation is determined by a different effect which is also calculated. The resulting formulae can be checked by experiment.