A regular chamber - Design of a test facility for the investigation of the reverberant sound field

Fundamental investigations related to the reverberant sound field are usually carried out in reverberation chambers. These are designed to achieve a high diffuseness of the sound field, which is often sought by a complex geometry of the chamber. An experimental limitation is that the size and shape of such chambers are fixed and changes can only be made by adding elements such as diffusers. This study presents the development of a chamber whose geometry can be modified to allow a high degree of control over the formation of the sound field in the room. The facility is called a regular chamber because its rigid boundaries form a cuboid. Nevertheless, two walls and a ceiling can be tilted independently so that the surfaces are parallel in pairs or not parallel at all, while the volume and absorption in the chamber remain approximately constant. The design of the regular chamber is presented, including the materials used and the principle for achieving the variable geometry. The test facility is used for experimental investigation of various concepts related to the reverberant sound field, such as diffuseness and mixing, in the context of modal and statistical descriptions.