Semi/Anechoic Chamber self build

[jordan bohan]

Hi Guys, I am new to this forum but was looking for some help.
I'm looking to do some sound testing on a boiler project of mine but require a space that is 30db or lower ambient sound, The boiler itself is required to run at 40-42db so I was told a chamber with a ambiant sound of 30db would be ideal,

Would anyone have any links to Anechoic chamber self builds or all in one units that might fit my purpose? the boiler that needs to be tested takes up a space of 500mm x 550mm x 2000mm,

I've seen some booths online that say they have "Sound-absorbing walls, floor and ceiling for an attenuation of 30 dB (measured according to ASTM E595, NIC value calculated according to ASTM E413)" Would this be what I need?

Any help you can give would be much appreciated,
Thanks in advance
Jordan

 

[Art Welter]

Jordan,

The ASTM E413 curve allows +20dB transmission at 125Hz compared to 1250Hz. Depending on the low frequency SPL at your location, and the actual attenuation curve of the both you are considering, an attenuation of 30 dB may not reduce LF SPL to 30 dB.

Also, a small "anechoic chamber" will not be anechoic at low frequencies, it will still exhibit room modes.

Art