The return of sound waves from surfaces on which they are incident. The geometrical laws for reflection of sound waves are the same as those for light waves. The apparent differences involve only questions of scale, because the average wavelength of sound is about 100,000 times that of light. For example, a mirror or lens used to produce a beam of sound waves must be enormously large compared to mirrors and lenses used in optical systems. See also Reflection of electromagnetic radiation.
A concave surface tends to concentrate the reflected sound waves. Convex reflectors tend to spread the reflected waves. Therefore, when placed at the boundaries of a room, they tend to diffuse the sound throughout the room. For this reason, some radio-broadcasting studios employ cylindrical convex panels as part of their wall construction to promote diffusion. See also Architectural acoustics; Echo;
