Measuring Sound Deadening Improvements

[scottrwalters]

Summary: I'd like recommendations for measuring noise in a moving vehicle before, during, and after applying sound deadening materials to my 2000 Passat.

http://packetpushers.com/scott/passat/passat.html

I've read a lot of the material in this wonderful forum but everything seems geared towards measuring systems in a non-moving car. I want to measure sound in the moving car environment with no stereo.

Here is a snippet from a post I made on ECA:

http://forum.elitecaraudio.com/showthread.php?threadid=136023

I think I got it. The "A" and "C" weightings are just algorithms to "average" the entire audible frequency range into a single number for "sound pressure."

Quite a lot of research has been done showing perceive loudness is not directly proportionate to sound levels. The human ear is much more senstive to certain frequency ranges (1-6 kHz). Apparently the "A" weighting is just a plain bad algortithm for measuring noise (which is
what we are after).

Apparently, the BBC and Europe, got it right with the CCIR 468 and later the ITU-R 468 weightings. Not only does is weight the 2-6 kHz frequencies more, it also deals with "masking" effects. A loud sound will desensitize
the ear to noise.

Check out wikipedia:

http://en.wikipedia.org/wiki/CCIR_(ITU)_468_Noise_Weighting

and loudness

http://en.wikipedia.org/wiki/Loudness

It would appear the ITU-R 468 will be a much better metric for our application. But I have not been able to locate any hand-held meters or software that
have this algorithm. Another thought is if you can record the sound and then analyze after the fact.

I also came across another algorithm called the articulation index: http://www.audiologyinfo.com/ai/aitut2.htm

I'd really like to develop a procedure that is repeatable so people could post data to the SDS site, before and after, with make, model, material, methods, etc.

TIA for any suggestions. So far, I've just used my Sony VX1000 to record footage in the moving car.

It boggles my mind the fact that sound deadening is a "must" in serious car stereos, and I've never once seen valid measurements showing an improvement. But anyone who has a clue can subjectively rave about the benefits.


Scott

McIntosh MX406
Butler 2150
DynAudio System 340
JL 500/1
JL 2x10W6v2

[Rudeboy]

I've actually tried this and corresponded with several people who've made the effort - none of us have had any real success, at least none of us have come up with any useful data. I have theories though :)

It's relatively easy to take measurments at idle. Start the car, let it warm up, take some readings, turn the car off, deaden and repeat. You should see an improvement.

But vehicle noise is much more than just the engine idling. To really get some useful information we should be able to take before and after readngs, on a variety of road surfaces at a variety of speeds. It's pretty easy to design the test course, but how do we set up to measure? The meters I have used are quite directional - makes sense since you generally want to point it at something to see how loud it is. My approach was to devise a mount that basically held the meter in front of the passenger seat head rest, pointing forward. Since I had already wasted a lot of time trying to tape record the difference, I went to great lengths to isolate the meter from the car. Thought I was good to go.

It turned out that my methodology sucked. Not only do you need an omni-directional mic to combine all of the sources that make up vehicle noise, but actually taking measurements is mcu more complicated than I expected. Vehicle noise is IRREGULAR. Many things combined. Very slight changes in course, speed and traffic can have a huge effect. Do you measure peak levels or averages? It quickly becomes obvious that what we perceive as a constant noise floor fluctuates dramatically on the meter.

I bought a half way decent meter for my tests, but one guy I corresponded with went even further - he bought a data logging meter that came with nice software to graph the measurements. He designed his course, measured, deadened then measured again. He graphed the data and showed no real difference. Glad I didn't go that far.

All of this had me wondering: is this all wishful thinking? No. I've also had the experience of deadening a car without the owner knowing I had done it. My girlfriend isn't exactly tuned in to her car. I actually taught her to drive (another story all together) and have been encouraging her to listen and watch for changes in behavior that might indicate problems. While she loves music, her idea of sound quality is her IPOD playing really loudly with all of the bass boost, etc., enabled.

She decided to make a quick visit home to Ireland and since I wasn't able to go, I had my chance. While she was gone I ripped her 2001 Saturn SL1 apart and deadened the hell out of it. Didn't touch anything else. Put the car back together and waited for her to return and drive it - after failing to get any useful metered readings again. That car was a noisy nightmare and it seemed to me that I had made it much quieter.

She returned and drove to work the next morning. I anxiously waited for her return and dreaded what struck me as the very real chance that she wouldn't notice any change. She pulled up, came into the house and said: "I think something is wrong with my car. The motor and wheels have gotten very quiet and for some reason the radio sounds much more powerful than before." Bingo. Blind test. Lest you think she was just being nice to me after I had gone to a lot of trouble on her behalf, you don't know the Irish :)

In any case, there is no doubt that sound deadening can make a dramatic change to ambient vehicle noise, not to mention the improvements in the sound quality of what we want to hear. Measuring it, not so easy.

[cotdt]

deadening seems to lower the frequency so the sound is more pleasant. i didn't measure a single dB in sound reduction, but subjectively it was much quieter. of course, most of the road noise comes through the windows anyway, since glass is a poor noise insulator. using multilayered windows with a dampening coat made an even bigger difference than dampening and i actually measured 3dB lower noise level.

[MIAaron]

This is pure speculation but it is my 2 cents. I see this as a very similar situation as when we discuss wood material for sub enclosure building. To get rid of the box talking (or in this case the sheet metal from vibrating) you have to mass load it til it is below the passband, or stiffen it til it is above the passband. In sub boxes the passband is the sub response, but in this case there are many sources of intruding energy that cause vibrations and noise. The amount of mass you add will kill some noise for certain freq's, but it will be a pretty narrow band. So for the most part you will still have the same noise/energy for the mic to read, but it will just be vibrating at a lower freq due to the increase in mass. Given that the mass of deadener is usually used to target the midbass freq's, our perception of less volume could just be our vastly decreased sensitivity to the lower octaves.

[Rudeboy]

This is pure speculation but it is my 2 cents. I see this as a very similar situation as when we discuss wood material for sub enclosure building. To get rid of the box talking (or in this case the sheet metal from vibrating) you have to mass load it til it is below the passband, or stiffen it til it is above the passband. In sub boxes the passband is the sub response, but in this case there are many sources of intruding energy that cause vibrations and noise. The amount of mass you add will kill some noise for certain freq's, but it will be a pretty narrow band. So for the most part you will still have the same noise/energy for the mic to read, but it will just be vibrating at a lower freq due to the increase in mass. Given that the mass of deadener is usually used to target the midbass freq's, our perception of less volume could just be our vastly decreased sensitivity to the lower octaves.

This makes sense for part of the phenomenon, but I'm not sure how much, for two reasons. When I first got started with sound deadening, I quickly concluded that mass loading and stiffening were the only real effects at play. Having since spoken to several scientists who make their livings designing vibration dampers for OEM application in automobiles and aircraft, I'm pretty well convinced that visco-elastic damping is more than the marketing hype I first assumed. If it were not, millions wouldn't be spent in development. That means real sound energy is being converted to heat and gone from the meter's realm.

The other example is the application of closed and open cell foam to the project. I have now done enough vehicles to make some comparisons and am convinced that they play a big role in the end result, again taking sound energy out of the equation.

As in so many things that deal with human perception of the physical world, I suspect that these and many other factors come into play.

[MIAaron]

Exactly, real visco-elastic damping that takes energy from mic and puts it into heat. Their example of a quiter ride yet the meter still reading the same isn't saying much for the damping effectiveness of their deadener. Maybe I just missed your point? :confused:

I don't see deadener as hype. It does what it does. But for a more quiet ride I'll take foam. Foam is awesome for actually absorbing sound. If you look at cars you don't see much deadener from the OEM. They use foam cuz it is much better suited for the application. As was pointed out to me by someone who has done more installs than I'll ever dream of, you'll occasionally see deadener on a car panel, and usually a later production model of that car will have a ridge or divet in that spot and no deadener. Sure the deadener will work to an extent, a layer of most materials will alter sound, but it doesn't mean it is the best solution. I'm sure there are many applications where visco-elastic dampeners work better. But automotive makers are good at finding a high cost-to-effectiveness ratio, and they choose foam to make it quieter in a car.

[scottrwalters]

It's relatively easy to take measurments at idle. Start the car, let it warm up, take some readings, turn the car off, deaden and repeat. You should see an improvement.


But what metric to use for our measurement? Based on my understanding of the standard A and C weightings for dB, they wont' cut it. Hmmmm.....since the noise should be pretty stable, would a standard RTA cut it?



But vehicle noise is much more than just the engine idling. To really get some useful information we should be able to take before and after readngs, on a variety of road surfaces at a variety of speeds. It's pretty easy to design the test course, but how do we set up to measure? The meters I have used are quite directional - makes sense since you generally want to point it at something to see how loud it is. My approach was to devise a mount that basically held the meter in front of the passenger seat head rest, pointing forward. Since I had already wasted a lot of time trying to tape record the difference, I went to great lengths to isolate the meter from the car. Thought I was good to go.

It turned out that my methodology sucked. Not only do you need an omni-directional mic to combine all of the sources that make up vehicle noise, but actually taking measurements is mcu more complicated than I expected. Vehicle noise is IRREGULAR. Many things combined. Very slight changes in course, speed and traffic can have a huge effect. Do you measure peak levels or averages? It quickly becomes obvious that what we perceive as a constant noise floor fluctuates dramatically on the meter.



Excellent observations, and after spending a lot of miles in my stripped car, I can conclusively say, perceived road noise is most directly related to the surface type your vehicle is rolling on.

I agree mic type and location are potential deal breakers for a consistent methodology, but my thought would be all data from a single vehicle would be collected the same way (same mic/recorder/position). I would be very specific about samples.

One - car stationary, engine off (control/baseline)
Two - car stationary, engine on (idle)
Three - car stationary, engine RPM at 55MPH
Four - car at 55 MPH on "asphalt"
Five - car at 55 MPH on "concrete"

Of course, no other cars around, and note temperature, humidity and wind conditions. Then the sound file would be analysed using another "standard way." The standard way of analysing is what I am after.


In any case, there is no doubt that sound deadening can make a dramatic change to ambient vehicle noise, not to mention the improvements in the sound quality of what we want to hear. Measuring it, not so easy.

Shouldn't be harder than the deadening job itself!

Scott

[scottrwalters]

deadening seems to lower the frequency so the sound is more pleasant. i didn't measure a single dB in sound reduction, but subjectively it was much quieter. of course, most of the road noise comes through the windows anyway, since glass is a poor noise insulator. using multilayered windows with a dampening coat made an even bigger difference than dampening and i actually measured 3dB lower noise level.

Wow, that's amazing. Could you please describe your vehicle and what materials/procedure you used for the "multilayered windows and dampening coat" ?

Also could you please describe your testing conditions such as meter, weighting, microphone, location, car speed, temperature, humidity, road surface etc?

Scott

[scottrwalters]

Exactly, real visco-elastic damping that takes energy from mic and puts it into heat. Their example of a quiter ride yet the meter still reading the same isn't saying much for the damping effectiveness of their deadener. Maybe I just missed your point? :confused:

That's exactly the point. I am trying to develop a method to quantitatively prove the effectiveness of sound deadening. By sound deadening, I am not constrained to any method such as vibration dampening, absorption, diffusion, or reflection. I want to measure the impact of these methods. Then from the data gathered, be able to make informed conclusions about the best way to treat noise in an automobile.

[QUOTE=MIAaron]
I don't see deadener as hype. It does what it does. But for a more quiet ride I'll take foam. Foam is awesome for actually absorbing sound. If you look at cars you don't see much deadener from the OEM. They use foam cuz it is much better suited for the application. As was pointed out to me by someone who has done more installs than I'll ever dream of, you'll occasionally see deadener on a car panel, and usually a later production model of that car will have a ridge or divet in that spot and no deadener. Sure the deadener will work to an extent, a layer of most materials will alter sound, but it doesn't mean it is the best solution. I'm sure there are many applications where visco-elastic dampeners work better. But automotive makers are good at finding a high cost-to-effectiveness ratio, and they choose foam to make it quieter in a car.

'Tis true, but along those same lines, we shouldn't add external amplifiers to our stock systems cause the factory doesn't do it that way. I am poking a little fun here, but car audio is extremely application dependent (car, SQL, SPL, compete/non-compete). Enthusiasts have a much different priority than car manufacturers.

And my two experiences don't support your installers observation. I've done a 1992 Toyota Camry and that vehicle had no dampening material, whereas my 2000 Passat had some (as seen in the pictures as the "black stuff" before I applied my mat). And my subjective recommendation would be, "if you have subs, you need dampening." Since the majority of factory systems don't have subs . . . .

I think we can agree that different materials serve different purposes for sound deadening in a vehicle. That is another motivation I have for improving the measurement methods. It would be great to have data that could support "for improved depth and detail, add foam" for "tighter bass, apply mat."

Scott

[Rudeboy]

Exactly, real visco-elastic damping that takes energy from mic and puts it into heat. Their example of a quiter ride yet the meter still reading the same isn't saying much for the damping effectiveness of their deadener. Maybe I just missed your point? :confused:


Sorry, I don't understand.

[Rudeboy]

The amount of OEM sound deadening varies dramatically between vehicles - generally, luxury cars have the most and many have a lot.

As far as developing an emperical scale for materials and effect, you have to consider that after market sound deadening is a very imprecise practice. The OEMs spend a lot of money to find the ideal peformance/price/weight/composition solution and use it for many vehicles. We just keep applying material until we think we have what we are looking for. We can't test the consequences of each gram we apply. I'd be willing to bet that half of what we do is wasted by deadening panels that don't really need it.

I fully understand the impulse to come up with numbers and encourage you to try. My only point is that it may not be feasible even for those of us who are strongly motivated but don't have access to advanced degrees and elaborate testing facilities.

[dbiegel]

It seems to me that it would be practically impossible to test by driving the car. Five degrees difference in temperature of the asphalt and/or tires could greatly change the noise levels created, not to mention having to drive on exactly the same part of the road (not on the crack in the asphalt an inch over from the previous run), changes in ambient sound, engine sound changes due to temperature, open/closed loop, etc etc.

Why not measure in a quiet, closed garage using a speaker OUTSIDE the car to create sound, and a meter inside? You could use different frequencies and different placements of it to simulate road noise from a tire, transmission through the door, etc. The only thing you wouldn't be able to measure would be chassis-induced noise (suspension, car body twisting, etc.) but that's a small price to pay for eliminating most variables.

[raamaudio]

What I have found is most people just do not want to take the time to analyze each part of their vehicle so they use the faster method known as the shotgun approach. I try to discourage that a bit by recommending to many, especially for performance cars,to only use what is needed in each specific area while applying mat.

matting the outer skin of a door does very little for road noise so if no speakers in the door I recommend to not use mat on the outer skin. Mat there is for stiffening the door skin and thus reducing the flexing, thus distortion of the acoustical energy if you have speakers in them.

For doors with speakers I recommend using one layer of mat on most of the outer skin followed by two more small patches right behind the speakers. That is all most vehicles need unless a pretty high powered midbass section is used in the doors. In that case I have added internal braces, etc. I also check lock rods, cables, wires, etc and if I can resonate I use tie wraps, silicone sealer, foam tape, etc.... to ensure it no longer will.

I always recommend sealing up the access holes in doors, I prefer to use a layer of metal, then mat, then foam. This is very effective in reducing road noise and most vehicles have allot to gain by doing so. It also stiffens that area and thus helps reduce distortion of the audio signal.

I also recommend to do the tap test on the back of door panels and add scraps of mat, then a good idea to cover it with foam, on just the resonate areas of the panels.

I then will recommend to use a dab of silicone sealer on the door mount pops, just enough to keep them from resonating yet still not to difficult to remove the door panel later if needed.

------------------

I have many more things I do on my own cars and recommend to others as well.

Depending on what the customer has intentions of achieving I vary the recommendations to suite their needs as much as I can. Also I consider their budget, audio install, how much time they wish to invest, etc.

Here are a few more things I like to do.

If doing a methodical job, use mat judiciously, use a rubber mallet, your fist, etc and find the more resonate prone areas and focus on them mainly. Since the floor of a car is subject to taking hits from rocks, etc, I like to cover the whole floor with mat then foam but the real trick is to do this. Once the first layers are put down go back and do the thump test and add a layer of mat, over the foam/mat layer already down, just over the bad areas. Then cover that with a layer of foam. You end up with mat/foam on most of the floor and on key areas mat/foam/mat/foam which is exceptionally effective but does not take allot of material or time.

In areas like behind the trim of a wagon I like to mat the wheel wells, again rocks, etc, strike them, and then just the rest of the areas that are more resonate prone, with mat. After that I like to cover the whole area, really everything I can possibly get to, with a layer of foam to deal with the higher frequency ambient noise. The more foam the better as it results in less reflected energy. It also is very cost effective and very low in weight. In my own vehicles I normally add a layer of 2" accoustical foam there as well, as long as I am sure no moisture can get to it.

In order to save weight yet have a pretty quiet roof I have just covered it with foam and then a second layer on the underside of the headliner, quite effective unless running a monster bass machine. On some installs it is best to mat the roof but I seldom recommend it.

I try to get all my customers to buy foam, not that I need more sales, it is hard to keep in stock as it is we go through so much. I do this because it is such a great improvement over just using mat alone, any brand of mat, as it has a very different purpose.

A side benefit is thermal, the particular foam we use is a thermal/acoustical barrier and it is very effective at both. I love having a cooler car in the summer and warmer one in the winter:)

I am also experimenting on different techniques on project cars we work on and have a few planned to test on our turbo Forester that would reduce the amount of materials used and give better results.

The last car we stripped down completely, removed all factory deadening, filled all body cavities with a really good quality and pretty stiff erathane foam (360 liquid oz), completely filled the area above the rear well wells(2 door hatch) and then used mat very carefully on just the areas that needed it.

The net result was a massively deadend car but only added 10lbs to the total weight of it. Of course there was the nearly 300 hours of work involved and pretty high cost of materials.

This project car was being built to race at the national level in a very fast autocross class, spend some time at track days on road courses and compete at the highest level in audio competitions.

One thing that really paid off was saving 46lbs by swaping the glass roof for a CF/Kevlar one(we were the only ones outside Toyota to have this roof;) It was much stiffer than the stock roof that was in three sections. I did not want to add weight up top but I did not want condensation problems and I wanted some noise control. The solution was to glue one layer of foam to the roof, then a layer of aluminum foil followed by a second layer of foam. The change was quite dramatic yet the weight gain was only a few lbs.
________________________

I love performance cars and not particularly fond of having them burdened with unnessesary weight(especially big sub units) so I have worked on methods or at least reduced amounts of materials stratigically placed for the optimum results and offer this advice to many enthusiasts weekly. (When we have the time we produce an underseat, great SQ with decent SPL 10" 17lb sub system for Subarus, it is a drop in under the front passenger seat)


An example of performance cars we like is the STI Subaru. Basically a factory race car with no sound deadening from the factory. Really fun car but not fun to live with daily. I have a basic package that literally transforms the car into something all together more comfortable to live with and improves the audio system a great deal at the same time. If done properly it can be acheived with just 20-22lbs of added weight and worth it, a very small percentage in a car that weighs around 3,300lbs stock.

If the owner is super weight concerned and is willing to do more specific work nearly the same results can be achieved with a few less pounds as well.

----------------

Though in the business to sell products I am very much into the business of helping my fellow enthusiasts achie their goals. I try to never oversell and I spend long hours every day and most weekends helping them figure out how to get the results they are after, very rewarding indeed, car guys are cool people!

-------------------------------

I could probably write a small book at least if not bigger on deadening a vehicle effectively in cost, time and materials, what I have mentioned is some of the bigger issues and some of the more obscure side of doing things.
-------------------------------

If I make somebody happy and for the least amount of expenditure as possible then I feel good about myself, I do not need to sell all I can to anybody, I get plenty of business from those happy with what I have helped them achieve. (Just tonight I advised two seperate potential customers to first fix their noisy exhaust systems then decide if they still wanted to deaden their cars, I would rather they fix the problem than try to mask over it and be unhappy with the results.)

---------------------------

I hope this does not come across as any sort of commerical for what I do, that is not the case at all. I wanted to let you know I do all I can to help others achieve thier goals first and foremost and give them ways to save time and money as much as possible, much of which means smaller orders from them but that is just fine:)

Mass loading has it's place, using foam has an equally if not more important part in this as well and many other methods, some of which are free:)

Sincerely,
Rick

[azngotskills]

Thanks for the write up Rick....very informative and useful tips that i need to utilize in my Celica :)

[rekd0514]

Yes, Thanks for taking the time to help people out Rick.If you remember, my name is Rick too. I know I looked at your guides and used some of the hints you told me in your emails when installing my mat. It helped me a lot in figuring out how to use the mat in the most critical areas. I think I achieved pretty good results with 1 roll and 3yds of Ensolite in my install and I am quite happy with it. It does take a lot of time and effort, but it will be worth it in the end if you use the tips Rick gives you.

Did you install all of your deadening in your Celica yet azngotskills?

[azngotskills]

I only did the doors and decide i was too lazy to use the rest so i sold it :( Bad mistake on my part becuse I realized how effective it was and now I need more for the upcoming install ;)

[raamaudio]

Oops, double post :o

[raamaudio]

Thanks guys:)

I did forget to mention I have tried measuring noise levels as well and also found it pretty difficult to come up with anything useful. I tried this with a hand held dB meter and the Audiocontrol RTA I used to own.

One more thing like to do, have as little reflective area as possible. I build panels under the dash to block it off but before I do I use a bit of mat where it is needed(HVAC, etc) and then glue foam over everything I can get to. I like to stuff a few chunks of thick real accoustical foam panels into some areas there as well.

I have reupholstered seats that were just part fabric and made them all fabric, made my own fabric headliners to replace vinyl, covered sides of consoles in carpet, whatever I can do and I use dash mats in all vehicles I can fit one in and look decent. (I may have to upholster the dash in my Forester as it does not look like a dash mat will fit very well)

I personally do not like leather interiors and would swap one out to fabric if I ever bought a car with leather, that is not even considering the negative aspects they have on an audio system which is quite significant.

I consider mat type products to be the foundation of building a good sounding car, there is far more to be done to get the best results.

Rick

[cotdt]

raamaudio: so leather in cars should be avoided? thanks for the advice, i will never buy leather seats again! i don't understand why people buy leather seats anyway. and i have also had a good experience with acoustical foam panels (the wedge kind).

i tried 4" foam wedges on my roof panel, the kind they use in anechoic chambers but shorter. i beleive the longer the wedges, the better it is at absorbing low frequencies. also, the more surface area, the more sound absorbed, so bigger cars are better all else equal. long story short: it made a huge difference and pretty much absorbed all reflections above 300Hz, and smoothed out the midbass as well. i still measured +-20dB peaks and dips in the bass region, so i guess i need longer wedges but too bad my car roof isn't tall enough for it. still, the improvement was amazing: totally killing all the annoying high frequency reflections.

several years ago, i read this magazine and they tested Dynamat in speaker enclosures using 3/4" MDF. there were 4 resonances, and while the Dynamat significantly lowered the two higher frequency resonances, it actually highered the two lower frequency resonances. overall it was still an improvement, though. i suspect that when we use dampening in the car, a similar effect happens and that's why the difference measured with a simple SPL meter is small.

[dejo]

as a complete noob on the subject, I would think that the dampening material would bring the frequency down where it isnt quite as noticable to the ear. I know this doesnt mean crap for a meter.

[theothermike]

why no leather seats? Im curious to the statement behind, never heard it before? what leather do? it disrupt the wave signal and reflects and stuff?

Mike-

[Hobbes26]

Leather is not as porous as cloth and thus does not absorb sound waves as much as cloth does.

[mk1982]

just want to clarify some definitions, is the inner skin the metal on the door closest to the driver (where the trim is attached) and the outer skin is where the door handle, lock etc is attached ? is that correct.

[Hobbes26]

Yep, that's correct. The inner 'skin' has all the holes in it and is usually covered with a plastic vapour barrier that should be removed when installing the mat and stuff.

[pontiacbird]

Once the first layers are put down go back and do the thump test and add a layer of mat, over the foam/mat layer already down, just over the bad areas. Then cover that with a layer of foam. You end up with mat/foam on most of the floor and on key areas mat/foam/mat/foam which is exceptionally effective but does not take allot of material or time.


On the surface, applying mat to the foam layer seems counter-intuitive, although I more than trust your recommendations.

Would one do a spot treatment of the foam, then apply the matting around the foam??

When dealing with a troublesome area, is this a superior method compared with mass-loading the respective area?? (just with regards to audible results, not the weight saving aspect)

Thanks again for the deadening tutorial you provided Rick, much appreciated!!!!! :D

[Rudeboy]

On the surface, applying mat to the foam layer seems counter-intuitive, although I more than trust your recommendations.

Would one do a spot treatment of the foam, then apply the matting around the foam??

When dealing with a troublesome area, is this a superior method compared with mass-loading the respective area?? (just with regards to audible results, not the weight saving aspect)

Thanks again for the deadening tutorial you provided Rick, much appreciated!!!!! :D

That's a DIY barrier along the lines of the foam de-coupled lead or mass loaded vinyl products you can buy for big bucks. As with any barrier, you have to "shield" against the noise source. Picture the space shuttle's heat shield. Unless there is complete coverage, the noise gets in.

[pontiacbird]

That's a DIY barrier along the lines of the foam de-coupled lead or mass loaded vinyl products you can buy for big bucks. As with any barrier, you have to "shield" against the noise source. Picture the space shuttle's heat shield. Unless there is complete coverage, the noise gets in.

I'll just trust the advice ;) ....I don't understand exactly the reasoning....but I will try this within the next week or so.

I guess it was naive of me to think pure mass loading would do the trick....as I'm somewhat underwhelmed at the results of my previous deadening job.

[Rudeboy]

I'll just trust the advice ;) ....I don't understand exactly the reasoning....but I will try this within the next week or so.

I guess it was naive of me to think pure mass loading would do the trick....as I'm somewhat underwhelmed at the results of my previous deadening job.

Start a new thread outlining your goals and situation and you should get some detailed help.