sound deadening
 

Just finished lining the doors, trunk floor, rear fenders, and rear speaker areas with "Brown Bread" (similar to Dynamat). Previous comments about the doors are correct; doors close with a solid sound and feel.
Results are as follows:
.................Before .........................After

idle..............67.............................. 67
60mph.........84..............................81
coast...........82..............................76
WOT............90..............................87

all in dbA

great test results for sound deadening

The only thing is that sounds very expensive and time consuming just to get 3-6 dBA of improvement. I imagine there is just too much structural-borne noise and noise leakage through the windows/seals to get any further improvement.

Interesting results though, thanks for posting the good info. :thumbsup:

I am not sure exactly how this works, but a 3 decibel sound reduction is significant; goes something like the sound level energy doubles every 3 db. Maybe someone else knows......Anyway, it is noticeable, and I thought, worth the effort.

Sounds cool. I've been wanting to do my doors for some time now. My questions are: about how much did the material weigh? And about how much did it cost?

i am pretty sure that this is right.
every 3dB = twice as "loud"

"Brown Bread" was lighter than the others, but I don't remember the weight. Less than a lb/sq.ft, I'd guess. I think 35 sq.ft was around $95

yeah, thats totally right about doubling the power for every 3 dB. However, doubling the "power" and doubling the "loudness" are two different things. In order to double the loudness, you would have to have a change of 10 dB. This is because the dB scale is a logarithmic function (based on multiples of 10). So doubling the loudness results in 10 more dB.

Even though this particular job hasn't quite decreased the loudness in half, 3 dB is still extremely noticible, so I'm sure its a lot more quiet in the car.

Awesome job! Wanna do mine next?

Rob

where can you get brown bread?

Great info.

Correct Rob, although that ratio of 10 dB to make a subjective halving/doubling of loudness does not work in the low frequencies where it occurs in as little as 5-6 dB.

True though that 3 dBA can be a noticeable improvement, especially since the A-weighting can hide much greater gains.

hmm... yeah, I didn't think about that, but you're right. In the lower frequencies, small changes in dB indicates a lot more amplitude, or loudness.

And the frequencies that you should be hearing while driving your car should be lower frequencies (unless you have your girlfriend riding with you, screaming in your ear. Those frequencies can be ear piercing).

Yeah, that small reduction will make a considerable improvement.

So how much of a pain in the a~~ was this stuff to install?

Shouldn't this go in the Interior/Exterior/Audio section?

Bought it from www.b-quiet.com. They sent no instructions- one tip it took me a while to figure out: cut the stuff with the backing paper on, then peel it. Not hard to do, once you are comfortable with removing the interior panels

Re: sound deadening
 

Thanks for the info!

I would think lining the firewall and entire floor (including under the center console) would yield even greater gains. I plain on lining the hood and engine bay firewall with stuff from www.heatshieldproducts.com

I'm going to do my interior this winter with plain old cheesy black vinyl door runner, some Reynolds wrap, and Super 99 spray adhesive - all in keeping with my Ghetto philosophy.:D

I was aiming for a 20db reduction, but seeing your results I should probably be more realistic and shoot for 10db - that would be huge!

Best thing I did to my RX7!
 

My doors were making all kinds of noises and the doors sounded so cheap closing.
Bought 50 sq ft brown bread on ebay for like $80 shipped.
I was so fed up that I put tons of dampening material in the doors.
I even put that stuff inside the door through the center hole and even inside the door plastic cover.
The result is amazing! The door closes solid like my S class Mercedes now and NO noises in the doors what so ever. Stereo sounds better too.
Will do trunk and fenders next. Don't care about the weight at all.