Noise measurement question 1

[MEP.Learner]

Hi,
Need some professional advices.

I have a project requiring to measure noise in accordance to Indoor Air Quality (IAQ).
I have doubts about the method statement of how this noise measurement should be taken.
Is it acceptable to just take the noise in dBA?
At what level and which point the noise should be taken? Must the height be fixed or it can be random? (deem that the noise level does not vary too much at about 0.8m to 1.5m from floor level.)

Lets say my ambient condition without AHU equipment running measured noise level at 55 dBA. And with the AHU turned on, i measured 68dBA.
How can i determine the noise level of the AHU alone? (without the ambient noise)
Any calculation that can be performed to get the AHU noise level?

Can anyone recommend some instrument / device with model no. that can measure noise in different frequency.

Thanks.

 

[GregLocock]

I think the answer to your first two questions will be in whatever spec you are using. If left to my own devices I'd use dBA to find the trouble spots and spectra to solve them. SLMs are often placed 1.2m above the ground. This discriminates against midgets but lets most people operate them.

As to your problem with dB arithmetic, AHU=10*log(10^6.8-10^5.5) which is pretty much going to be 68dBA

Random googling led me to this instrument, it seems pretty typical

http://www.nti-audio.com/en/products/xl2-sound-level-meter.aspx

Personally I would go for a decent multichannel A/D on a laptop with a decent mic, single channel stuff is fine for surveys but not for problem solving.



Cheers

Greg Locock


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