Hello,
I've to admit that I don't really understand your description of the situation.
Anyway, if you're worried about fasade sound insulation windows will always be the weakest point. Second, damping materials are, so to speak, not used in building acoustics. Bricks, concrete, gipsum, glass...
Hello Paulo,
you should expect between 10 and 20dB attenuation with an enclosure. that is 10dB attenuation isn't that bad but there's place for improvement.
what I see at first sight is that your enclosure might not be good enough to block the low frequencies related to a big fan. You should...
Thanks for your information Emmet,
Yes, it's close to a residential area. I got the idea of playing the "scream" of a seagul's ennemy in a loudspeaker. Not I've to find wether seaguls have ennemies and who they are...
OkdB
Kæffer in Germany has microperforated acrylic panels as well as microperforated polycarbonat foil named microsorber.
http://www.kaefer.com/neuhome/microsorber/e_hauptset.htm
Acrylic panels are sold in North America by RPG diffusor under the name Clearsorber...
Well, I got a good question today from a client having a problem with seaguls: would it be possible to hold the seaguls away by means of sound "uncomfortable" to birds but non-perceivable by humans?
I don't know if seaguls are sensitiv to ultrasound. Does anybody know? Who has a...
Hello,
There's many things that can go wrong. Here's some:
1st, look wether there's a silencer installed on the duct line. If not, get one!
2nd, the air speed is too high. A high velocity air flow would generate a high frequence noise in the louvers.
3nd the fan isn't operating correctly...
Hello,
Try this manufacturer: Trelleborg-Novibra http://www.trelleborg.com/industrialavs/
They know what they're talking about, have a wide range of product and they sell almost every where in the world.
OkdB
Hello TomFitz,
First, the results you got appear awfully high to me. The noise limits used in Norway for HVAC is 40dBA.
Second, you got many answers which are a bit to complicated for your application. Your meter is good enough. Measure the sound level in the middel of the room or close to the...
Hello,
I'm not sure about what you're really look after, but if you want to acoustically isolate pipes, you can use common mineral / glass wool cintered in a aluminium / steel sheet with tickness of 0,5 - 0,7mm. Any insulation contractor can do it for you. But be sure at first that this is the...
Hello,
I'm far to be a spesialist in structure, but my guess is that you should test the structure for the machine with the lowest frequency in order to prevent any resonance and eventually, have the possibility to isolate vibration from the machines. To isolate vibration properly, the...
Hi,
Maybe it's a stupid proposal, but if the machin has its own supporting structure, would it be possible to separate that structure from the building? no contacts, no vibration transmission, right?
OkdB
Hi again,
I though about it and the vibration source could be just the fan. hence, it migth be necessary to isolate just the fan with a concrete base with spring isolators and a flexible copling to the wind tunnel.
OkdB
Hi,
i don't know exactly how your wind tunnel looks like, but i assumed it's big and that you can't have it on vibration isolators for stability reasons. I think that the only solution to reduce structure borne noise to other rooms is to mount the wind tunnel on a vibration isolated concrete...
Just some tips,
air springs have almost none sideway strength. So, if your vibration are in 1 direction, 1 axe, it's ok, or else you have to install air springs in every axes.
Second, air springs have a large displacement. Check wether this wouldn't interfere with the good function of the...
Hi PacificSteve,
How to calculate sound levels from sound powers:
Lp = Lw - 20log(r) - 11 (free field, 1/1 sphere)+ 3dB for each reflection plan (for ex. ground reflection, wall,...)
By the way, I'm not sure that formula works in US units, so use METRIC UNITS to be sure.
"r" is the...
