Sound Deadening: Closed-Cell Foam

[coronajm 10+ year member]

I have researched alot on sound deadening and i noticed that an increasing amount of people are supplementing with closed-cell foam on top of the deadener. i somewhat understand the proclaimed benefits, but is it really worth it for the price point? after this 200 sq ft purchase of deadener, i am finding it really hard to spend another $100 on materials like Ensolite. can enyone justify its value and really help explain what it does? not much on the search.

thanks

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[Trixter 10+ year member]

egg crate foam, wal-mart, bedding section, cheap

i wish i had a nickle every time i posted this....

 

[JohnnyChuttz 10+ year member]

I bought one of the thin sleeping pads in the camping section at Wal-Mart. I coudnt't find it on walmart's site but like this.

http://www.summitcampinggear.com/coreeapad.html

Cost ~$5 and a tube of liquid nails. I did up both sides of the inside of my doors.

 

[dumple 5,000+ posts]

i agree with ^ i did 2 layers of peel and seal and a layer of that and its pretty nice sounding

 

[squeak9798 5,000+ posts]

I have researched alot on sound deadening and i noticed that an increasing amount of people are supplementing with closed-cell foam on top of the deadener. i somewhat understand the proclaimed benefits, but is it really worth it for the price point? after this 200 sq ft purchase of deadener, i am finding it really hard to spend another $100 on materials like Ensolite. can enyone justify its value and really help explain what it does? not much on the search.
thanks

They perform two very different functions.

There are two different types of deadening; Mass loading and barrier loading.

Mass loading would be your typical sound deadening mat such as Raammat or Second Skin Damplifier or Damp Pro. Their purpose is to add weight to the panel to reduce panel vibrations and resonances. They do little to nothing in terms of actually absorbing sound waves.

Barrier loading is exactly the opposite; Their sole purpose is to absorb/deflect sound waves but do little to nothing in terms of reducing panel vibrations/resonances (unless you were to stick it between two panels that happened to be vibrating against each other creating a noise.....but that's neither here nor there). This type of product would be your foam products and deflex pads, such as Ensolite or Overkill (I think that's what SS calls theirs).

So what you need to decide is whether you want to only stop panel vibrations/resonances, or if you want to reduce resonances aswell as absorb sound waves which helps you both control the acoustic enviornment inside of the vehicle aswell as reduce road noise, etc.

 

[coronajm 10+ year member]

thanks for the breakdown squeak. now that i know of the cheaper solutions everyone suggested above, i will definately look into getting one of those sleeping pads or similar type foam. also, to johnnychuttz and dumple, did you guys do any sort of weathertreating the foam before installing it?

thanks

 

[HCCA 10+ year member]

i agree with ^ i did 2 layers of peel and seal and a layer of that and its pretty nice sounding

Peel & Seal will melt, and fall off the inside of your doors after a few days of intense summer heat. FYI

 

[Shyne151 10+ year member]

Peel & Seal will melt, and fall off the inside of your doors after a few days of intense summer heat. FYI

I had peel and seal in my monte carlo for over two years, and never had a piece fall off... maybe you just need to know what you're doing? not saying i'll use it again(hated the smell), but it never fell off.

 

[audioholic 5,000+ posts]

I would have to disagree that deadening mat does little or no sound absorption. I do agree that is not their main purpose, but deadening mats can and will block/absorb some sound waves.

I consider most mat today as 80% mass loading, 20% sound reflection/absorption... while closed cell foam is 100% sound absorption and 0% mass loading (or anything else).

Just find a cheap alternative closed cell foam (like ones already suggested in this thread) and place it in strategic areas like doors, wheel wells, firewall, etc.

 

[CaliforniabOY5 10+ year member]

I just find it hilarious how most people are only looking for shortcuts and alternatives rather then doing them thoroughly and taking pride in a complete non-half assed job.

 

[Ninteens 10+ year member]

Peel and seel will not fall off if its applied correctly. I've had it on the sides and roof of my truck for two years.

My truck sat through a full Texas summer and nothing sagged or fell.

Its all in the surface prep!

I have tried using the blue foam sheets that are used for the sides of houses. They don't do anything really, and standard 3M spray glue will dissolve the foam. Now thats a big mess! But just because I tried something different doesn't label me as a crappy installer.

To reply to CaliforniabOY5, doing a job using non standard materials doesn't necessarily mean that your doing a half-assed job.

I for one think that the prices company's charge for common installation materials is outright robbery. Best-buy is one of the prime examples.

For example the Rockford Fosgate 20ft 12 gauge speaker wire roll, sells for 19$ but best-buy pays like 3.05$ for it.

 

[audioholic 5,000+ posts]

I just find it hilarious how most people are only looking for shortcuts and alternatives rather then doing them thoroughly and taking pride in a complete non-half assed job.

What are you talking about?

 

[squeak9798 5,000+ posts]

I would have to disagree that deadening mat does little or no sound absorption. I do agree that is not their main purpose, but deadening mats can and will block/absorb some sound waves.
I consider most mat today as 80% mass loading, 20% sound reflection/absorption... while closed cell foam is 100% sound absorption and 0% mass loading (or anything else).

Honestly you are arguing semantics.

Even using your figures (which if you have any actual data to support, I would be interested in seeing) I would consider 20% to be little, as I stated. Since for some odd reason people on forums like to describe a sub's output and sound quality attributes using percentages; If you said a sub had "80% SPL and 20% SQ", how would you likely describe it's accuracy? You would probably say it had little accuracy.

Yes, mat deadeners are going to reduce structural noise and are going to have the ability to block some noise/frequencies entering the cabin.

It's barrier loading properties are relatively poor, especially compared to something designed to function in that capacity (such as foams). If you are wanting to absorb sound and combat airborne noise, mat is not going to be very effective.

 

[Envoy62 10+ year member]

The sound deadening materials add mass to the panels and by this shift their response to excitation caused by the sound pressure that the speaker emits. Sound pressure is basically just moving air pressure. When that pressure is hitting a large panel it will cause the panel to vibrate and so the panel by itself will emit noise. The panel becomes a speaker membrane so to speak.

Now if you apply a deadening to the panel you add mass and now the same amount of sound pressure on the deadened panel will cause less deflection of that panel and by this cause less noise. The deadening is reducing structure borne noise.

Now the closed cell foam has an other function it is used to reduce air borne noise. You could describe it as insulating the side of the panel were its applied ( inside of door ) to the other side the passenger compartment were you sit and listen to the music and want to attenuate any undesired noise from the exterior. The way this works is the sound pressure is converted to heat inside the foam. Both have their specific purpose and if applied correctly will be helping you to improve (lowering the back ground noise in the case of the foam and reduce structure born noise in the deadening mtl. case).

If you look at anechoic chambers in acoustical labs thei are specified to give a certain attenuation in db's. What that means is that for example if you have a chamber that is rated to have a 30 db attenuation and that chamber is placed in an environment that has a65 db ambient noise level the background noise level in that chamber will be 35 dB. This is also what you try to achieve by applying foam on top of deadener to you car. Insulating the cabin so that external noise is not getting inside the cabin.

I have read some comments from people sying that application of the foam resulted in no audible change. What i have to tell you is that in order for this to work you will need to do a very go job in closing all potential channels from the exterior of the car into the inside. Otherwise your efforts might not yeld the desired results. One would need to make sure that all openings gaps etc will be covered with the foam.

One has to judge to which extreme one wants to go. What i would suggest is that people check their car very well to see if there are any openings that lead to the outside or to the engine bay and make sure that all of these are plugged as good as possible otherwise application of the foam will not be very effective.

Regards

Robert

 

[IgnoreMe 5,000+ posts]

just to argue the peel and seal point...i used that shit on a completely unprepped surface in my doors. didnt notice much midbass increase but whatever...as far as sticking good...the shit stick and sticks good. it sticks so good im pissed i put it on cause i cant get it off //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif//content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

i regret puting it on