Thx - Interesting... only Abstracts are free - unless you visit a Univ. Library with an engineering Dept - at state univ.'s they will typically be in X S.U. places, not the U. of X. places - i.e. the Morril Act "Cow Colleges - like UC Davis & Cornell:D)

Most of these will be impractical for us. However,
2007-01-2186
Automotive Sound Absorbing Material Survey Results
- sampled 128 types of porous materials and found that the key was air permeability - the ability of air to move thru the material ("specific air flow resistance "). No single material was best overall. Might be nice to know which commercial materials were sampled.

I invite others to scan thru these Abstracts and post a condensed version (as per above) of the ones that are interesting for our purposes. There are tons of engineers on the board, several pro sound people, and at least one scientist. IF we divide up such tasks, we could probably make pretty fair progress.

Another idea I had is that we could all -ah- "spam" Road & Track tech writer Dennis Simanitis to compare a 1960s luxury car with a modern one in terms of noise levels. If there has been a lot of progress, then that should show up there.

And as one person above noted, wouldn't it be nice to know what Porsche and Ferarri are using for sound reduction materials these days??
Anybody have a 997 I can rip apart?

Yes,.."interesting", I'd say, too.

MANY areas are covered, helping the layman reader to better understand the complicated noise sourcing in this (audio) wideband environment....most, out of your control (as I hinted way, way back). "practically" certainly would not apply to those things out of your control....

As to a passive approach for noise reduction (with limited weight),..yes,..the data can be "whittled down"....one will choose his battles, as to perfection. And there are MANY battles to choose based on your goals (i.e., "with minimal weight expense").

What are you alluding to with the "Morril Act" observation? (I ask this sincerely,..and I may say that I do know about about the Morril Act [[[[or should I say the "Morrill Act", 1862]]]] but want to be sure). Cow colleges ? Am I looking in the wrong places? Just asking... as I've many other sources of research data......

I'll be glad to get an email to "Dennis Simanitis" (actually, I thought his name was Dennis Simanaitis,..do I have it wrong here?)..


Onward with the project....amen.

Best,

Doyle

e.g Oregon State Univ. has their engineering school - it was est. by the Morrill Act (Land Grant College Act).

Univ. of Oregon does not have an Eng. school so don't go there to find SAE publications.

I thought there was another "L" there.....

I thought International SAE papers were "SAE" papers....(wherever you may find them). Are you saying they're no good?

Best,

Doyle

Guys,

I do understand that many of the SAE papers are for members only($$$), but I'll pass on anything that you guys' need (as I'm a member, longstanding)...sorry for any brickwalls you may have hit.


Best,

Doyle

Guys,

Just a url for your indulgence....the more the merrier (info, that is):

http://findarticles.com/p/articles/mi_m3012/is_7_183/ai_105659483/pg_1?tag=artBody;col1

...and be sure to hit ALL pages,..glass man,...glass!!!!

Best,

Doyle

no, good - not no good

mmm,..interesting,..actually: amazing....! ( I was hoping for a "yes/no")

Further reads along the fear and loathing trail of sound reduction in the 911 tub...:::

(again,..just for consumption)

http://www.adhesivesmag.com/Articles/Cover_Story/aefef62f1fac8010VgnVCM100000f932a8c0____

http://www.secondskinaudio.com/products/Noise-Reduction.php

http://www.automotive.basf.com/p02/Automotive/en_GB/portal/show-content_powertrain_chassis/content/Our_solutions/Powertrain_and_Chassis/Noise_reduction/Noise_reduction

http://www.automotivedesignline.com/showArticle.jhtml;?articleID=193700417

http://www.automotivedesignline.com/showArticle.jhtml;?articleID=57703010

http://trj.sagepub.com/cgi/content/abstract/76/11/813?rss=1

http://www.atzonline.com/index.php;do=show/site=a4e/sid=546166438486ada6403562919877766/alloc=3/id=7622


more underbody stuff:


http://www.canadiandriver.com/articles/jk/031008.htm
http://www.msnbc.msn.com/id/25248338/

(yeah,..I know,..MSNBC).................


Happy reading(s).....

Best,

Doyle

Subscribed.

I haven't pulled any new 911's apart but I noticed the 993's have a thick, foam like padding on the floor boards.

I also recall someone removing about 200 lbs of sound insulation and back seats from a 996 for the Lap of American.

So it sounds like the sound insulation in the new cars is even heavier than the old ones.

Heavier would not surprise me - these cars are built for certain customers, and the buyer of the average new Porsche is not the same customer that buys the old ones. But we could use a thinner, lighter example of the new sound material if it is better (i.e more attenuation per unit thickness). We could also benfit from new techniques used by P AG or others.

re a 993, i wonder if Bill Verburg would be willing to rip apart his in the name of science...

Randy, wouldn't it be easier to look for a local 993?

Just put an ad in the newspaper for a heavy Oregon donor.


Badum Bum...ting!

I've been looking for a sound deadening study for a long time and haven't come up with much; if someone can find just some benchmark data on various materials I'd be dancing. The end game is that heavy things reflect/absorb sound energy. Lead is one of the best sound deadeners available. Concrete is very good, glass is pretty good as it does have a significant density. To the best of my knowledge "light sound insulation" is pretty much an Oxymoron.

Latest Autoweek has a piece on the new Aston Martin. Not many changes, just refinements. One of those, AM reports, was running down and closing up some 1100 "pathways" allowing sound to travel from outside the car into the passenger compartment. 1100! I think you guys have your work cut out for you.

That is not correct. You are thinking of sound dampening materials, not materials that absorb sound.

The latter, are a relatively new development and consist of small ('micro') beds encapsulated in a matrix material. The vibration of the sound is attenuated because it is "captured" and emerges as motion. I assume this is motion of the micro-beads. In other words, the sound is turned into heat (only tiny amts. of heat are generated in this process).

Then, there are aero-gels....

http://www.grc.nasa.gov/WWW/AcousticalTest/Industrial/Vibration_Control.html

the inner door panel and rear parcel shelf should be isolated from the body with foam or aerogel. This would make the inner panel or rear shelf a sound wall.

Rusnak: that's a sweet reference...gonna' take some time to digest....


Best,

Doyle

Moneymanager: "nail on head, bud".

Best,

Doyle

I'm waiting for all you smart people to figure this out and tell me what to buy. :)

see above

beyond that, you will mostly be buying labor... we can surely cut the 1,100pathways down to a few hundred that are most important...