Acoustical Testing Facilities

Our laboratory staff has more than 30 years of combined experience in acoustical testing and noise control technologies. We leverage that experience in RAL’s sophisticated testing environments.

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1940s Absorption Test


One of the first of its kind in the world, Room 0 is a highly reverberant sound chamber with a volume of 292 cubic meters. This room is isolated within a second room that is located inside the main building. Both the test chamber and second room have 45 cm thick walls and 68 cm thick ceilings.

Because of stringent temperature and humidity requirements designated by certain acoustical test standards, Room 0 is controlled within 1°C and 2 percent relative humidity for each test. The chamber has the necessary fixed and rotating diffusers to randomize the sound field. Room 0 is primarily used for sound absorption, sound power, sound pressure, and dB(A) type measurements. Adjacent to Room 0 is a temperature-controlled work and curing area where specimens can be prepared before testing.


Each of these temperature and humidity controlled test chambers contain 50 cm thick walls consisting of two separated columns of high density solid concrete blocks. Thus, after a test specimen is installed between Rooms 1 and 2 or Rooms 3 and 4, there are four block walls totaling 100 cm of mass and separating airspaces to avoid sound escaping into the adjacent room by other routes (flanking paths).

To achieve high ratings on various test assemblies, double-metal flanking shields have been installed to provide additional isolation. The laboratory walls, poured concrete floors, and pre-stressed, reinforced concrete ceilings contain the appropriate isolation and flanking path eliminators required for sound transmission and sound impact tests. Fixed and rotating diffusers are in place to provide a randomized sound field to satisfy precision requirements.