The Anechoic Doak Laboratory facility is approximately 15m x 7m x 5m high and is fully anechoic down to 400 Hz. It is used for jet and valve noise and is equipped with an air supply that can achieve up to 20bar pressure. Both polar and a transversable azimuthal array of microphones can be used to give a complete 3-dimensional sound field up to a maximum acquisition frequency of 40 kHz.