This chamber’s floor is acoustically reflective, while the walls and ceiling are covered with sound-absorbing wedges that do not reflect sound. This allows it to measure sounds stably in an environment that is quiet and unaffected by weather conditions. The background noise at the center of the chamber when the door is closed is less than 20 dB. The floor area of the room is 15m x 15m, which allows the chamber to receive up to medium-sized trucks and perform measurements from a sufficient distance.