An anechoic room simulates a free field — a representation of a theoretical infinite space, in which there are no sound wave reflections (echoes). In rooms such as these, the only sounds which exist are emitted directly from their source, and not reflected from another part of the chamber. Anechoic rooms have the characteristic of being muted, muffled, and silent.

An anechoic room is used for making acoustic measurements with microphones and loudspeakers.