Sound Pulses Radiated in Air by Creeping Waves on Rigid Spheres and Cylinders

Abstract

The diffraction of sound pulses by metal spheres and cylinders in air was observed under conditions where the radiation from creeping waves could be compared with the specularly reflected pulses. The amplitudes of the radiated and reflected pulses were compared for various angles of scattering and for a range of frequency parameter (ka) from 8 to 20. The results were in agreement with theory in the case where the calculations were available. The attenuation of the creeping waves was determined from the decrease in amplitude of the sound pulses radiated tangentially as the creeping waves traversed increasing arc lengths along the surface of the body. In the case of pulses derived from truncated sinusoids two or three cycles in duration, the attenuation agreed with the steady-state theory in the observed range of frequency parameter from 8 to 40.