Electronics engineers use anechoic chambers for electromagnetic compatibility (EMC) or electromagnetic interference (EMI) and RF testing. The interior walls of these chambers are treated with special material to absorb electromagnetic waves. There are also audio anechoic chambers, designed for applications such as audio recording, that absorb sound waves rather than electromagnetic energy.

There are three main types of acoustic test chambers:

• Hemi-Anechoic Rooms. In a semi-anechoic chamber, only part of the room receives acoustical treatment. For example, the walls and ceiling may be designed to absorb sound energy, but not the floors. Hemi-anechoic rooms are generally used for automobiles, construction equipment, heavy appliances (e.g., refrigerators, washing machines), and other items that operate directly on sound-reflective surfaces such as floors and roads.
• Full Anechoic Chambers. This type of chamber is designed to absorb up to 100% of the sound energy within its walls. Its surfaces are covered with anechoic material and its floor is designed to support heavy test specimens. Full anechoic chambers are often used for speakers, microphones, and other equipment that requires reverberation to be kept at a minimum.
• Pass/Fail Chambers. As its name suggests, this chamber is designed to test whether a specimen meets the acceptable standards of acoustic quality. Pass/fail chambers accommodate devices like mobile phones, computer equipment, and others that don’t need to be tested under hemi-anechoic or full anechoic conditions.