Air‐filled spherical shells in water have been insonified by a pulsed sinusoidal beam with a carrier frequency of 2 MHz. Experimentalkavalues ranged from 47 to 550. The bulk of the investigation was directed toward the spheres with the largerkavalues; and for these, experimental results are compared with computations made for the intensity distribution in reflection from a perfectly reflecting spherical surface. It is found that the agreement is good if the thickness of the shell is less than 1/10 wavelength, but that marked departures occur for shells of appreciable thickness (of the order of a sound wavelength in the shell material).