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  1. okdb

    How to reduce noise from highway rumble strips in motel

    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...
  2. okdb

    Noise Reduction in a blower with fiberglass

    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...
  3. okdb

    Hearing spectrum for seaguls

    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
  4. okdb

    perforated glass

    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...
  5. okdb

    Hearing spectrum for seaguls

    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...
  6. okdb

    Noise from HVAC in the church! How do we reduce?

    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...
  7. okdb

    Elastomeric and AV mounts

    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
  8. okdb

    Metering Sound in HVAC

    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...
  9. okdb

    Looking for supplier of Acoustic Blankets for topside pipework

    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...
  10. okdb

    Multiple machine vibrations

    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...
  11. okdb

    Information on Pneumatic Isolators?

    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
  12. okdb

    aeroacoustics in wind turbines

    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
  13. okdb

    aeroacoustics in wind turbines

    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...
  14. okdb

    Information on Pneumatic Isolators?

    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...
  15. okdb

    Sound pressure level for new ACCU

    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...
  16. okdb

    Noise map software

    Agree with you JFPELVIEW that those programs can easily give you some weirds answers and one should always make som samples measures in order to get a clue of what noise levels should be expected. This kan be however difficult to do in practice, especially if your talking about noise levels from...
  17. okdb

    Noise map software

    Thanks Vozgul, I knew about IMMI but it doesn't use the nordic calculation method, unfortunately. OkdB
  18. okdb

    Noise map software

    Hi, We're looking for a noise mapping software for noise from traffic, railways and industries. We have to use the nordic calculation method to comply with the authorities. There's only to softwares that calculate with this methode: SoundPlan and CadnaA. Both programs do a lot of thing and it...
  19. okdb

    Noise reduction in deisel generators

    Hi, Technically you'll need at least a good exhaust muffler and a good soudproof box around the generator with a ventilation system with silencer on the air inlet and outlet. OkdB
  20. okdb

    Noise Cancellation

    Hi, My advice: try good old sound insultation. It works and isn't that expensive. I'm not sure what kind of false ceiling you have and how extensive it's the problem, but if you need 3 dB reduction or so, try to lay a 100mm tick layer of dense glass wool like AF-75 over an area about 3m x 3m...

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