A conducting chamber used for electromagnetic compatibility and acoustic testing. An antenna is placed in the chamber along with the product under test, which is then subjected to electromagnetic fields in order to determine the radiated susceptibility of the product. All of the walls, the floor, and the ceiling are covered with material designed to absorb reflections that may interfere with the direct energy radiated from the antenna to the product. The action of the chamber is to screen the high fields inside from electrical equipment external to the chamber.

A semianechoic chamber is similar to the anechoic chamber but the conducting floor is not covered with the absorbing material. Here the chamber is used in a similar mode to the open-area test site to determine the radiated emissions of the product. The semianechoic chamber has the advantage that there are no ambient signals present but it may limit the volume available for the test.