An anechoic room, also called a dead chamber, is a space in which it is desired to reproduce, inside an envelope, the propagation conditions of the sound in a free field i.e. by freeing itself from the reflections of sound waves on the partitions, like for the situation observable outdoor.

anechoic room
Anechoic room or dead room
   

Depending on the needs, it may be either a semi-anechoic chamber (the floor is reflective) or an anechoic chamber (the floor is also absorbent), the anechoic behavior being made possible by the implementation of materials with the highest possible absorption coefficient (i.e. as close as possible to 100%) in the frequency range of interest, whose low limit is often referred to as the cutoff frequency (and is expressed in Hz).

When it does not consist of dihedrons of absorbent materials (wedges), the lining of such an acoustic measurement room can be flat, if the technology of compact broadband absorbers is used (being based on a multilayered acoustic structure, with a rear resonator for the absorption of the low frequencies and with a front dissipative material for the absorption of the medium and high frequencies, leading to a lower thickness, which is significant when it comes to improving the performance (e.g. by decreasing the cutoff frequency) of an existing room whose boundaries must be maintained).

In particular, the determination of the sound power levels (expressed in dB ref.1 pW) emitted by the noise sources from the acoustic pressure (whose levels are expressed in dB ref. 20 μPa) is possible in an anechoic room or in a semi-anechoic room (by laboratory methods), with respect to electro-acoustic equipment and devices, machinery or other sources of noise, provided that their dimensions are compatible with the measurement area given the dimensions of the testing space (which can sometimes accommodate vehicles).

Such measurements are subject to specific international standardization, namely through the ISO 3745 standard, which is often used by acousticians for their research and development in acoustics, which can also intervene in the field of psychoacoustics.

In addition to the particular characteristics of anechoic behavior, a dead chamber often has performance in terms of sound insulation, if it comes to characterize the noise emissions of equipment for which a low background noise level is required or to limit the transmission of noise emitted by tested hardware from measurement rooms interior towards contiguous premises..

If it is appropriate to consider the eventual dismantling of the testing equipment in case of a future possible relocation, an envelope made of modular metallic acoustic insulation panels may be an appropriate construction system.

ITS can participate in the design and construction of your acoustic test facilities and of your test benches.