Anechoic Background Levels 1

[COWBOYME]

Does anyone know of a standard for background SPL in anechoic or semi-anechoic chambers?

 

[GregLocock]

No, but how about 20 dB below the SPL of your test specimen?

You also have to be very careful about where you measure the noise - if you hve any ventilation or whatever then things get complicated very quickly.





Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[COWBOYME]

Thanks Greg.

I was thinking that way too, but wanted to make sure I met Stds if there were any. Anyway, always good to confer with another engineer before telling the boss you're going to spend a lot of money.

Regards

Tom Ballas

 

[GregLocock]

I helped spec a SAC with chassis dyno, for vehicle noise work. I think something like half the budget for the chamber went on air handling.

We certainly didn't meet 20 dB at all frequencies of interest.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Rob45]

Why don't you ask this question of one of the mfrs of anechoic chambers?

I'd recommend Eckels, and I'd strongly recommend against Industrial Acoustics who have gone downhill since Martin Hirschorn sold the company.

Regards,
- R

 

[aathi1]

I would suggest to be below 10dB and also what you need to measure in the chamber. Last year Eckel built us a hemi anechoic chamber with back ground noise at 8dB.

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Regards,

Balan.G

 

[IRstuff]

Standard rule for instrumentation is ratio of measurand to uncertainty of 10:1.

TTFN

FAQ731-376