Anechoic chambers are rooms or spaces constructed with the interior surfaces lined with anechoic wedges providing up to 100% absorption of the incident sound energy, making them echo-free. These chambers are commonly used in acoustics to conduct experiments in "free field" conditions, free-field meaning that there are no reflected signals.

In such an environment, sound energy radiates outward from the source with almost no reflection. This makes anechoic chambers ideal for tests like measuring the frequency response of loudspeakers and microphones.

Inside an anechoic chamber, noise levels are extremely low—typically between 10 and 20 dB. Since the average human ear can perceive sounds starting at around 0 dB, the space may feel completely silent. Some individuals find this level of quiet disorienting and uncomfortable.

In an audio anechoic chamber, all sound energy from an external source travels outward with negligible reflection. This ensures that only the direct sound from the test object is captured. In contrast, conducting the same test outside of an anechoic chamber would result in the microphone picking up both the source sound and unwanted reflections or reverberations.