ALT Facilities
Qualification of free-field environments for anechoic rooms
Qualification of free-field environments for anechoic rooms and hemi-anechoic rooms
When sound waves travel from a sound source and arrived at an object, the waves will be absorbed by the material, and the remaining power of the waves will be reflected. In any enclosed space that has rigid boundaries, reflections will occur. Studying some behavior of sound in these reverberant sound field might not be accurate.
What is an “Anechoic Chamber”?
An anechoic chamber is a chamber or a room where a free sound field is obtained. The room has been designed to have no reflection of sound, by absorbing all sound waves that incident to the room boundaries. Walls, floor, and ceiling are fully lined with sound absorption material (acoustics wedges). In an ideal free field, the sound behavior will follow the “Inverses square law” where a sound pressure level will drop by 6 dB when the distance from the sound source increase by double.
What is a “Hemi-anechoic Chamber”?
A hemi-anechoic chamber has the same design principle as an anechoic chamber. The room boundaries are lined with acoustics wedges, except for the floor. The floor of a hemi-anechoic room is a rigid hard surface, which makes a hemi-anechoic room perfect for studying the sound behavior of a heavy-load sound source.
Standard test method
ISO3745: 2012
Annex A — Precision methods for anechoic rooms and hemi-anechoic rooms
ISO3745: 2012
Annex A — Precision methods for anechoic rooms and hemi-anechoic rooms
