Noise Testing dBA

[umatrix]

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 ?

 

[dgallup]

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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[MintJulep]

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?

 

[GregLocock]

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


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[btrueblood]

Or better, if testing say, loudspeakers.