Author Topic: Auto sound-proofing  (Read 6919 times)

Mark H

  • Guest
Auto sound-proofing
« on: January 04, 2001, 06:19:21 AM »
Yeah, I know it isn't possible, but I want to reduce the noise levels in my Nissan Pathfinder 4x4.
Undoubtably the most noise transmits through the floor (I have BFG All Terrain tires, and of course the 4 WD drivetrain etc) I measured the sound in the cabin, windows up, smooth freeway at 65 mph. It was 72-74 decibels dbA, and 96 dbC. I aim to reduce that a lot.

I was going to use 3 different barrier materials on the floorpan and firewall- One layer asphalt based mass loading sheet (call it Dynamat) for vibration. Then a layer of 1/4" Vinyl nitrile foam, and top off with a layer of mass loaded vinyl sheet.
Doors- one layer Dynamat on outer skin, one layer on inner skin, one layer mass loaded vinyl under the trim panel.
Roof, one layer 1/4" vinyl nitrile foam in between the roof and the headliner (I have a roof rack that whistles at freeway speeds).
Questions:
1) Some people just put 2 or 3 layers of Dynamat on the floor and call it done. But this is not really going to do much for low frequency sounds is it?
2) Should I put 2 layers of Dynamat, then the foam and vinyl sheet, or will one be enough?
3) OK, what I'm really getting at- Is my floor treatment overkill, or not enough?
Can anyone think of anything I should be doing differently?
Thanks
Mark


bjnash

  • Guest
Re: Auto sound-proofing
« Reply #1 on: January 06, 2001, 05:50:28 AM »
: Yeah, I know it isn't possible, but I want to reduce the noise levels in my Nissan Pathfinder 4x4.
But it's not only possible, but practical!
: Undoubtably the most noise transmits through the floor (I have BFG All Terrain tires, and of course the 4 WD drivetrain etc) I measured the sound in the cabin, windows up, smooth freeway at 65 mph. It was 72-74 decibels dbA, and 96 dbC. I aim to reduce that a lot.
:  
: I was going to use 3 different barrier materials on the floorpan and firewall- One layer asphalt based mass loading sheet (call it Dynamat) for vibration. Then a layer of 1/4" Vinyl nitrile foam, and top off with a layer of mass loaded vinyl sheet.
Our vinyl foam is not durable enough to use on the floor, use in the doors, trunck, hood, etc
: Doors- one layer Dynamat on outer skin, one layer on inner skin, one layer mass loaded vinyl under the trim panel.
: Roof, one layer 1/4" vinyl nitrile foam in between the roof and the headliner (I have a roof rack that whistles at freeway speeds).
The foam will perform well here.
: Questions:
: 1) Some people just put 2 or 3 layers of Dynamat on the floor and call it done. But this is not really going to do much for low frequency sounds is it?
Yes, but our vinyl sheet will work better.
: 2) Should I put 2 layers of Dynamat, then the foam and vinyl sheet, or will one be enough?
Don't use the foam, it's not going to perform well here.
: 3) OK, what I'm really getting at- Is my floor treatment overkill, or not enough?
: Can anyone think of anything I should be doing differently?
: Thanks
: Mark
Normally, you only need the mass loaded vinyl on the floor.  
Bj Nash, Super Soundproofing Co, 1531 AVOHILL DR, VISTA, CA 92084-1325  PHONE: 760-749-7049  8-6 5 Days




Mark H

  • Guest
Re: Auto sound-proofing
« Reply #2 on: January 08, 2001, 05:53:50 PM »

: Normally, you only need the mass loaded vinyl on the floor.  
BJ,
Are you saying to dispense with the Dynamat on the floor completely, and just use mass-loaded vinyl?
You suggest using vinyl nitrile foam in the doors. Is it waterproof? As you know car doors are "wet" environments, last thing I want it a sponge soaking up and retaining water on the inside of the steel.
Thanks for the response, I appreciate all the info.
Mark


bjnash

  • Guest
Re: Auto sound-proofing
« Reply #3 on: January 09, 2001, 05:36:10 AM »

:
: : Normally, you only need the mass loaded vinyl on the floor.  
: BJ,
: Are you saying to dispense with the Dynamat on the floor completely, and just use mass-loaded vinyl?
: You suggest using vinyl nitrile foam in the doors. Is it waterproof? As you know car doors are "wet" environments, last thing I want it a sponge soaking up and retaining water on the inside of the steel.
: Thanks for the response, I appreciate all the info.
: Mark

Yes to both, it is waterproof because it's a closed cell foam.


 

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