Greetings,
We must assess the noise attenuation of a sound enclosure designed to contain a 135 dBA noise source with a reduction of 50 dB. The noise source is not yet active and won't be until late September, but an assessment of the noise enclosure is necessary for payment purposes.
A preliminary noise survey measured the following levels:
[ul]
[li]Noise OUTSIDE the booth: 65 dBA[/li]
[li]Noise INSIDE the booth (door closed): 35 dBA[/li]
[li]Total reduction: 30 dB (nowhere near the 50 mark).[/li]
[/ul]
Here goes the question: should I worry about the above, or is the apparently poor performance due to the booth not being designed to attain low noise levels inside?. What I mean is that the booth doesn't have the kind of provisions you would see in a semi-anechoic chamber, such as floating floor, resilient mounts between main structure and concrete floor of the warehouse, etc.
At the moment there is no way to test the booth with a noise source inside, unfortunately.
Some facts about the noise enclosure:
[ul]
[li]The booth has only two apertures, 24x12 in each. Each aperture leads to a silencer rated for 55 dB, one silencer is for the inlet air flow and the other one is for the outlet air flow.[/li]
[li]There are no windows.[/li]
[li]All walls and the roof are made of a double layer of special acoustic panels. The combined weight of both layers is 10 psf[/li]
[li]The panels have one noise-absorbent face, both layers have the absorbent side facing inwards the booth.[/li]
[li]There is a 1" cavity between both layers of panels and they are fastened to the main structure with C profiles with resilient neoprene between the panels and the profiles (there are no studs in the middle of the walls)[/li]
[li]The smallest wall is 13x10 ft, the largest is 16x10 ft[/li]
[li]The roof is 16x13 ft, double layer, made in two sections 8x13 ft each. It too has no studs separating the inner and outer layers[/li]
[li]The combined wall materials have a rated noise reduction in excess of the 55 dB as per lab certification[/li]
[li]The door is also rated more than required, lab-certified.[/li]
[/ul]
We must assess the noise attenuation of a sound enclosure designed to contain a 135 dBA noise source with a reduction of 50 dB. The noise source is not yet active and won't be until late September, but an assessment of the noise enclosure is necessary for payment purposes.
A preliminary noise survey measured the following levels:
[ul]
[li]Noise OUTSIDE the booth: 65 dBA[/li]
[li]Noise INSIDE the booth (door closed): 35 dBA[/li]
[li]Total reduction: 30 dB (nowhere near the 50 mark).[/li]
[/ul]
Here goes the question: should I worry about the above, or is the apparently poor performance due to the booth not being designed to attain low noise levels inside?. What I mean is that the booth doesn't have the kind of provisions you would see in a semi-anechoic chamber, such as floating floor, resilient mounts between main structure and concrete floor of the warehouse, etc.
At the moment there is no way to test the booth with a noise source inside, unfortunately.
Some facts about the noise enclosure:
[ul]
[li]The booth has only two apertures, 24x12 in each. Each aperture leads to a silencer rated for 55 dB, one silencer is for the inlet air flow and the other one is for the outlet air flow.[/li]
[li]There are no windows.[/li]
[li]All walls and the roof are made of a double layer of special acoustic panels. The combined weight of both layers is 10 psf[/li]
[li]The panels have one noise-absorbent face, both layers have the absorbent side facing inwards the booth.[/li]
[li]There is a 1" cavity between both layers of panels and they are fastened to the main structure with C profiles with resilient neoprene between the panels and the profiles (there are no studs in the middle of the walls)[/li]
[li]The smallest wall is 13x10 ft, the largest is 16x10 ft[/li]
[li]The roof is 16x13 ft, double layer, made in two sections 8x13 ft each. It too has no studs separating the inner and outer layers[/li]
[li]The combined wall materials have a rated noise reduction in excess of the 55 dB as per lab certification[/li]
[li]The door is also rated more than required, lab-certified.[/li]
[/ul]
