# Lab space



## glaufman (Nov 25, 2007)

This may be unusual for this forum, but here it goes...

I have a laboratory space in our just-moved-into building at work where there is some equipment that vibrates our products for lifetime testing... in our old building we never measured SPLs above 80dB for more than 2 secs at a time...

In our new space, we're registering average, semi-sustained readings of close to 90dB, which I find concerning. I don't have the dimensions of the space at my fingertips, but it's fairly standard construction... linoleum/vinyl tile over concrete floor, drywall on metal studs, drop ceiling. One wall is concrete block.

I'm hoping that the fact we're in a different space (that may be a smaller volume than the old lab) points to having increased reverberation times, and that the increase in SPL is due to "buildup" due to those reverb times... as such I'm hoping that putting acoustic absorption into the room (specifically behind and opposite each of the loud pieces of equipment and on that concrete wall) could significantly reduce the overall SPL in the room... I'm looking for at least 5, preferably 10dB...

I don't have the ability (in the next day or two at least) to take accurate measurements to see exactly what frequencies are present (although one of my guys thinks he's going to measure it with an app in his i-phone, but don't get me started on that)...

Do I stand a reasonable chance here? Am I barking up the wrong tree?


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## bpape (Sep 14, 2006)

Nope - it's noise. Music or equipment - still noise. First thing I would suspect is that the entire new structure is being vibrated by the equipment more than the old one was - or the old building had more 'holes' in it to let sound out, or both. Yes you can seriously vibrate a concrete slab. 

While you can use treatments to diminish the decay times certainly, you won't reduce the initial SPL. For that you would want to use some sort of a 'barrier' around the equipment that would act as a layer of mass to reduce transmission into the rest of the space and an absorbing layer to catch it earlier. If it's still an issue, then you'd need to look into in isolation mount for it. That's very common for larger equipment to stop vibrations into other parts of the building.

http://www.acousticalsurfaces.com/mounts_springs/neoprene_isolators_r_rl.htm

http://www.acousticalsurfaces.com/noise_barrier/bardec.htm

Other things available but just a couple of links to give you some ideas. Might also want to look at the 'external barriers.'


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## glaufman (Nov 25, 2007)

Hi Bryan... thanks for the reply...

While I'm aware that treating the walls won't alter the "initial SPL" as you say, the question more geared towards, will it reduce the reading on the SPL meter, which I assume is a combination of the initial, or direct sound, and the reflected sounds... thoughts?

For the sake of argument, we're measuring this A-weighted, to comply with OSHA standards...

I have a new set of measurements this morning, showing at most a 3dB difference between A and C weightings and it's not consistent, varying as the overall SPL varies, and sometimes A is higher, sometimes C higher... for this reason I think we're not dealing with low F's (say below 500Hz or so? maybe 200Hz is a safer number to use)... thoughts?

My theory is to absorb what I need to in the lab first, and then worry later about whether or not it's necessary to isolate from the rest of the building... thoughts?


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## bpape (Sep 14, 2006)

If you don't want to use a barrier (which I would recommend) you'd need to treat pretty much the entire room.


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## glaufman (Nov 25, 2007)

For the barrier... you prefer the product you linked to over a floor-standing version of GIKs panels?

Reason I ask is whatever we put up as a barrier has to leave space for hoses cables, vents to go into and out of the machinery, as well as being easy to move/remove for regular maintenance...


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## bpape (Sep 14, 2006)

Our panels do not have any mass that will stop sound. They are purely absorbers. The ones I linked to have a layer of mass and some absorption also.


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## glaufman (Nov 25, 2007)

So... to reduce the sound inside the lab, the barrier would effectively need to be almost wrapped around the machinery in question?


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## bpape (Sep 14, 2006)

Yes - that's correct and then just a cloud overhead to help to absorb some of what is getting out at the top.


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## glaufman (Nov 25, 2007)

Might give that a try. But I'll have to figure out how to make it work with all the goes-intos and goes-outas for that...
Do they have any prepped solutions for making self standing panels out of that?

(I've been looking but can't find so far myself)


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## bpape (Sep 14, 2006)

Not that I know of but likely could be easily built from PVC pipe.


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## phazewolf (Feb 5, 2012)

I am going out on a limb with this but would isolation from the slab (think rubber feet) help in a case like this?


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## bpape (Sep 14, 2006)

It's possible that it could help a little - likely moreso to adjoining rooms but it could be setting up low frequency issues inside the room. Hard to tell without a frequency analyzer.


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