The echo returned by a body is known to be frequency dependent if the incident sound has wavelengths greater than or comparable with the over‐all dimensions of the body. Unfortunately, a theoretical investigation into such a dependence involves lengthy computation since exact mathematical solutions are required. In this paper the results are presented of calculations which determine the echoes from the end‐on aspect of a rigid prolate spheroid of fineness ratio 5/3 and from the beam‐on aspect of an infinite circular cylinder, the incident sound consisting of plane monochromatic waves. These are compared with similar known results for a sphere. It is shown for these particular examples that the frequency dependence of the echo varies significantly with the shape of the body which returns the echo. It is suggested that bats use such properties in determining the form of their surroundings.