The study of speech requires the availability of a recording environment with very low ambient noise and reflected sound. An anechoic chamber is a room in which the walls, ceiling and floor are lined with a sound absorbent material to minimise reflections. The research anechoic chamber is lined with glass-fibre wedges whose shape enables free-field conditions to exist above 90Hz. In addition the chamber is constructed as a room within a room. The outer walls are 330mm thick and the inner room is formed of metallic acoustic panels mounted on a floating floor. This results in a very low noise environment in which the sound pressure due to outside levels is below the threshold of hearing. The chamber is equipped with a Bruel & Kjaer 2231 Sound Level Meter and Laryngograph. Signals are routed to an adjacent control room containing a Sony DAT recorder and a PC. A prompting system is available for presentation of the recording material on a ceiling mounted monitor.
Here is an interview between Steve Nevard and the BBC's reporter Mike Williams, about UCL's Anechoic Chamber.
Further details about the properties of this chamber can be found in the below document: