Types of chamber include anechoic, reverberation and the gigahertz transverse electromagnetic cell (GTEM cell). Foam absorber is used as lining of anechoic chambers for electromagnetic radiation measurements. Free field conditions can be artificially produced in anechoic chambers. A compact range is an anechoic chamber with a reflector to simulate far field conditions. Full anechoic chambers aim to absorb energy in all directions. An anechoic chamber is also commonly used. Measurements made outdoors will approximate well to anechoic conditions. In April 2003, an anechoic chamber test facility was established. Pressure-based measurement methods are widely used in anechoic conditions for noise quantification purposes. Anechoic chambers are expensive for several reasons and are therefore not common. It has the only anechoic chamber in the region. Anechoic tiles were added later to reduce noise levels. This fact is exploited to measure sound power in anechoic conditions. In recent years, nearly all modern military submarines are designed to use anechoic tiles. The Japanese "I-400" super-submarine also used anechoic tile technology supplied by Germany.