Simple Explanation

Echo-free. An anechoic room has no reflected sound because its surfaces absorb nearly all sound energy.

Concise Technical Definition

The complete absence of reflected sound, achieved by using materials and geometry that absorb or dissipate sound waves, as in an anechoic chamber.

Layman-Friendly Analogy

Like shouting into a giant pillow fort—no echo comes back, just silence after your voice.

Industry Usage Summary

Used to describe specially designed acoustic test rooms (anechoic chambers) that absorb nearly all reflections, simulating a “free-field” environment. Critical for speaker testing, microphone calibration, and precise acoustic measurements.

Engineering Shortcut

Anechoic = zero reflections; free-field condition.

Full Technical Explanation

"Anechoic" describes environments in which sound reflections are entirely eliminated or reduced to an extremely low level, typically using angled, wedge-shaped foam or fiberglass materials on all room surfaces. These chambers simulate a free-field acoustic environment, meaning sound behaves as though it exists in an open space with no boundaries. Anechoic chambers are used for accurate measurement of microphones, loudspeakers, and acoustic devices, where even slight reflections could distort test results. Reverberation times are often below 0.1 seconds, or effectively immeasurable.