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Noise Testing dBA

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umatrix

Mechanical
Jul 18, 2013
62
Hello Eng-Tips,
I am testing a component in an anechoic chamber. The data is reported in dBA.
First test results in a 55 dBA level
Second test is 59 dBA
My question is what is considered significant or noticeable with dBA? I understand that dBA is frequency weighted, but not sure how to report 4dBA change , significant or not ?
 
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3 dB is considered distinctly noticeable. If you listen carefully 1 dB can be discerned. 10 dB is considered twice as loud.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
 
Same component and same conditions? Why so much variation?
Or is it measurement uncertainty?
What is the allowed limit? 58 dBA? 60 dBA? 100 dBA?
 
Assuming your test method is valid, a 4 dBA shift is well outside any repeatibility limits, as it represents a doubling of emitted sound energy. Therefore it is a real effect (and quite a big one, I have rarely managed 4 dBA without significant mechanical changes). An expert evaluator would probably rate it as 2 points worse (on a 10 point scale).

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
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