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NIWelcome to the acoustic anechoic chamber! What exactly is this space? A specialized room where NIST researchers can make acoustical measurements without an echo.
All six sides (including top and bottom) of the room are covered in fiberglass wedges that absorb sound with the bottom floor covered by an additional layer of wires suspended a few feet in the air. This is where electroacoustic devices, such as microphones, loudspeakers and hearing aids, are measured.
The room is surrounded by concrete walls that are 0.3 meters thick and sits on 52 coil springs to reduce vibrations from the outside.
Because of these features, sound that is generated inside the room gets absorbed by the walls. There’s practically no echo or reverb down to 45 hertz and the wedges absorb 99 percent of the sound that hits them.
Another aspect of the room design is that sound from outside stays outside (which explains how quiet it can get in here!).
NIST researchers use this chamber for research towards developing documentary standards – official ways to specify test methods or procedures - for hearing aids. One example includes standardized procedures for measuring the directivity index, a parameter that is commonly used to characterize the performance of directional hearing aids.
Researchers also provide data regarding the characteristics of these devices to the U.S. Department of Veteran Affairs.
#Sound #Measurements #SoundProof #Standards #Electroacoustic
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