sound barrier material
12-20-2005, 05:32 PM
#1
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does anyone have any experience with sound barrier/absorber material (not talking about mass dampers, eg dynamat, b-quiet, etc). i've seen some of the companies sell this stuff for an arm and a leg it just looks like closed cell foam with an adhesive layer. is there any certain criteria or type of foam that is better than others for sound barrier properties? what about alternate materials like rubberized undercoating from canadian tire? is there really much difference between that and the liquid sound deadner/sludge?
12-20-2005, 06:36 PM
#2
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The liquid stuff acts the same as the mass dampers, not a barrier/absorber like you wanted..
But whats wrong with b-quiet? they sell a barrier/absorber.. Here http://www.b-quiet.com/vcomp.html they also have a l-comp barrier to.
I would buy one of those.
But whats wrong with b-quiet? they sell a barrier/absorber.. Here http://www.b-quiet.com/vcomp.html they also have a l-comp barrier to.
I would buy one of those.
12-20-2005, 07:37 PM
#3
Each material will absorb different frequencies at different levels. I'm using 3 different types of foam in my home theater (Ester, Ether, and Melamine).In my case they range in thickness from .5" to 6" thick. But you can get foam that's really thick. The shape will also effect the sound absorption (look at an Anechoic chamber). From my testing, there are differences from one foam to another. Melamine seems to absorb the best from my experience. But I doubt the differences will be noticable in pieces that arent very thick.
12-20-2005, 08:08 PM
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well, the v comp is nice, but pretty expensive. i've heard the liquid stuff has more sound absorbing properties than asphalt/butyl mat. honestly, i've heard a friend's car that is deadened with b-quiet ultimate and it's not much quieter. better bass response tho.
i know a wave form would be the best shape for the foam but given the restrictions of installing in a car i think plain sheet is the only practical way to go. how dense is the melamine? there is a local shop in kitchener that sells foam in bulk so i'm thinking of picking up some 1/2" closed cell to try in the car. i'm also real curious about the rubberized undercoating. i'm thinking of buying some in bulk and trying it on top of the mass deadener i'm going to install. i wonder how much it really does.
i've got an srt-4. anyone who's ridden in one knows how loud they are, so i'd like to get things a bit quieter on the inside.
i know a wave form would be the best shape for the foam but given the restrictions of installing in a car i think plain sheet is the only practical way to go. how dense is the melamine? there is a local shop in kitchener that sells foam in bulk so i'm thinking of picking up some 1/2" closed cell to try in the car. i'm also real curious about the rubberized undercoating. i'm thinking of buying some in bulk and trying it on top of the mass deadener i'm going to install. i wonder how much it really does.
i've got an srt-4. anyone who's ridden in one knows how loud they are, so i'd like to get things a bit quieter on the inside.
12-23-2005, 01:31 AM
#5
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I have conversed with Mark Eldrigde quite a bit on this subject. A barrier and absorber have imensely different prooperties. I use Bquiet pretty much exclusively in my Beetle and found that a couple layers of mat and a layer of LComp works the best for me. As you try to absorb lower frequencies the thickness of the foam has more to do with the effectiveness. For me B Quiet is the most cost effective solution.
12-23-2005, 08:42 PM
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i took a look at what raammat offers. they've got a 1/8" thick closed cell foam available. i can get a closed cell foam that 3/8" thick for the same price in canadian dollars locally. but is this better sound barrier material? beats me? i guess the only way to find out is try it. i think i will try out some rubberized undercoating while i've got the interior stripped out for installing the deadening. does anyone know if it's better to put the undercoating on first or put it over the deading mat?
12-23-2005, 09:06 PM
#8
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sure it is. industrial earplugs are made of foam. no lead in those. sound studios are surrounded in foam that acts as a barrier/absorber. undercoating does act as a sound barrier as well. at least the tar/rubber stuff.
i think you might be confusing mass damping with sound damping. i've heard (and with first hand experience) have seen that mass dampers (dynamat etc) generally do little sound damping. i don't think l or v comp would be very effective without the foam.
i think you might be confusing mass damping with sound damping. i've heard (and with first hand experience) have seen that mass dampers (dynamat etc) generally do little sound damping. i don't think l or v comp would be very effective without the foam.
12-23-2005, 09:37 PM
#9
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^ and you are assuming that a barrier is the same as a absorber.. Which it is not.
Hers a quick link to read:
http://members.shaw.ca/soundcontrols...d_barriers.htm
Here is a commerical sound barrier used in construction:
http://www.silentsource.com/barriers-soundbarriers.html you will notice it is made of vinyl, just like v-comp.
There are basically 3 different ways of controling sound.
1) Mass Dampers. This stuff adds mass to a) reduce vibration (so you dont feel the door/floor vibrate) and rattles, b) lowers its resonance so it doesnt transfer sound, this has a small impact on lowering road noise. mass dampers are dynamat sheets etc.. as WELL as the liquid type including the undercoating spray etc. The mass needs to be applied directly to the panel to increase its weight.
2) absorbers.. This is the foam you see in studios etc.. they work BEST at reducing reflections, improving sound quality. Yes they can have a impact on road noise (etc.) but thats dependent on thickness.. which with road noise will only improve it slightly.
last is 3) barriers. they work TONS better at reducing road noise then the other 3, because thats what its made to do.
l-comp and v-comp has nothing to do with mass damping as it doesnt add mass to the vehicles panels. the vinyl/lead is the barrier, and the 1st layer of foam decouples it from the car, the 2nd acts as a absorber.
[ December 23, 2005, 10:46 PM: Message edited by: chev2 ]
Hers a quick link to read:
http://members.shaw.ca/soundcontrols...d_barriers.htm
Here is a commerical sound barrier used in construction:
http://www.silentsource.com/barriers-soundbarriers.html you will notice it is made of vinyl, just like v-comp.
There are basically 3 different ways of controling sound.
1) Mass Dampers. This stuff adds mass to a) reduce vibration (so you dont feel the door/floor vibrate) and rattles, b) lowers its resonance so it doesnt transfer sound, this has a small impact on lowering road noise. mass dampers are dynamat sheets etc.. as WELL as the liquid type including the undercoating spray etc. The mass needs to be applied directly to the panel to increase its weight.
2) absorbers.. This is the foam you see in studios etc.. they work BEST at reducing reflections, improving sound quality. Yes they can have a impact on road noise (etc.) but thats dependent on thickness.. which with road noise will only improve it slightly.
last is 3) barriers. they work TONS better at reducing road noise then the other 3, because thats what its made to do.
l-comp and v-comp has nothing to do with mass damping as it doesnt add mass to the vehicles panels. the vinyl/lead is the barrier, and the 1st layer of foam decouples it from the car, the 2nd acts as a absorber.
[ December 23, 2005, 10:46 PM: Message edited by: chev2 ]
12-24-2005, 08:31 AM
#10
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David is right. Foam is an absorber, not a barrier. As far as the foam making an effective absorber, the thickness of the foam is the most important determing factor in which frequencies are attenuated. the foam has to be thicker to absorb midrange frequencies.
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