Noise Control (Sound Vibration Damping)

Nice, the floor on the Gen III is a little different than the Gen II, looks a little bit flatter actually. I couldn't get rid of the stock cloth pads because they were contoured to fit the uneven floor:





Please keep the updates coming, nice to see someone is going through the same pain/obsession I did!

- D

 

I had a BMW and a Lexus before my Prius. Love my Prius so much but I do have to turn the radio up higher! Seems to help with noise issues!!!

 

So far you've got a LOT better floor coverage with the MLV than I do. I'm worried that you'll have trouble getting the carpet back in to be honest! But you should see some good results. A lot of the noise comes from the front wheel wells and it's difficult to get them blocked from inside the car .
That MLV ("sound blanket" as you've been calling it) is at least 1lb/sqft, the V-MAX is .35lbs/sqft. VB-2 isn't so bad for weight and you didn't use a whole lot. But you can do the math from there based on how much you bought and what's left over.
I used SecondSkin Damplifier and Damplifier Pro (similar to V-MAX) as well as some VB-2. Then for the MLV I used SecondSkin's Luxury Liner Pro. Paul at Cascade told me that it's the same stuff as their product actually. Cascade, SecondSkin and SDS (SoundDeadenerShowdown) seem to have the best products and customer service based on everything I've read and my contact with all of them.
I did take readings with a RadioShack sound meter. But I think I messed it up. Reading the directions they advised using "A" weighting for measuring background noise. So that's what I did on the "before" test. Then on the "after" tests I didn't find a measurable improvement. Even after replacing my crappy OEM tires with nice quiet Michelins the sound meter didn't show any measurable change. So I'm thinking I should have used "C" weighting. But I also didn't get nearly as much coverage as you are doing with the MLV, which as Cascade's Paul explains is critical.
I did the doors, rear cargo area and floors. The doors made a huge improvement on how good the door mounted woofers sound. It's funny, what started out as a project to reduce road noise turned into a stereo upgrade as well. Still a work in progress.
Full photo reviews here:
Prius Second Skin - Photobucket
Prius Audio upgrade - Photobucket

- D

 

Don,

Did you notice an improvement even though you had trouble measuring it? I'm too busy and/or lazy to do the whole car like you guys are doing and I imagine it would cost a lot to have it done, but I am considering doing the doors just to limit some vibration in the door material and cut the direct sound coming through the door.

 

As usual with my DIY projects, once I had it done I'd finally learned enough about it that I wanted to start over and do it differently! But it was fun.

The main improvement I noticed from just doing the doors was the improved sound from the speakers. Another plus is the more solid "thunk" you get when closing the door - no more tinny ring to it. Road noise seemed a little better but it could have been all in my head. Most of the worst road noise comes from the front wheel wells in my opinion.

The claim made by Don Sambrook at SDS (Sound Deadener Showdown) is that you don't need full coverage with the vibration damping. Called Constrained Layer Dampener (CLD) these thick foil backed butyl mats can be stuck on with just 25% to 50% coverage of the larger areas of sheet metal and be very effective.

I did 100% coverage in the door with an inferior product (eDead 80) and wish I'd done less with better. Both from a weight added and effort expended perspective. But as I'm sure Gwest will agree, once you get going it's hard to resist just covering everything!

In hindsight I like Cascade Audio VB-2 or the thicker VB-2HD for the door inner skin like Gwest did, very tidy and effective without too much weight. The CLD mats on the outer skin are the best choice there. Recommend either V-MAX from Cascade, Damplifier Pro from Second Skin or the CLD tiles SDS sells. Don at SDS is a small one man operation and you need to email him to order, but he's a great help.

To actually block sound effectively you have to use the MLV (Mass Loaded Vinyl) products in addition to the CLD, like Gwest is doing on the floor. Hanging MLV in a door would be very challenging and prone to disaster if it fell off and blocked the window from going up and down. People do try it though. Another approach is to cover the inner skin of sheet metal with it, or even the inside of the door trim panel. But that gets difficult to make the panel fit back on well. Again, people have done it but it's not to be taken lightly. Hope that helps!

- D

 

Those are pretty amazing differences when you consider what the dB scale means: "... each three decibel increment affects a 50% change in sound pressure levels. Thus, a 3 dB drop reduces sound exposure by 50%, while a 6 dB drop reduces exposure by 75%. Though reducing the decibel level produced by a sound source from 80 to 77 may not seem like a major change, it would actually represent a 50% reduction in audible sound."

So in other words, well done! Must feel positively plush compared to before.

- D

 

Go test drive one...not that they'd let you take it on the freeway...

I'm torn...I'd love to quiet down my car, but I'm not up for tearing the whole thing apart like you're doing, Gwest. Impressive work!

 

I'd like to compliment the OPs on their handiwork and diligence on jobs well done.

I think it should be emphasized that it is not necessary to cover every square of metal with damping material, let alone double cover it. The same goes for sound absorbers: It is more important to place it in critical locations that everywhere.

Damping material is changing the resonant frequency of the part, be it a door trim panel or a metal skin, and it happens when the mass and weight distribution of the part is changed. Ideally, it would make a part completely rigid. This can be done without covering the whole piece. Think about it, the floor pans could be made much more rigid by reinforcing them with appropriate placed rails and using thicker sheet metal or just by making the the whole floor pan out of inch thick plate steel--which is analogous to 100% coverage; overkill, impractical and expensive.

My guess is that high end vehicles do not have 100% coverage.

Sound absorption is another matter, once sound waves are created in a space, the appropriate absorptive material can trap them if the waves come in contact with the material. Sound absorptive material could also change the resonant frequency of the substrate that it is attached to, but most often it seems that it is not heavy enough to be effective. The converse is true, too: sound deadening material could absorb sound if constructed properly. It is probably easier, though, just to use two materials.

I think that many of the companies selling these products have an obvious conflict of interest and are also guilty of being a little thin on true audio & engineering expertise.

The take home message is to use the materials judiciously and put the savings into better speakers and equalization. Too bad there isn't a glass upgrade for these cars. (But that would add a lot of weight).

 

Just running this topic around again as it seems to be relevant and pertaining to a few....

I haven't done it yet - but am getting ready to when I do my rear speakers (kinda doin it all at once). I had the doors (front) apart - but don't remember (didn't measure) how thick I can go... I'd like to run a thick acoustic foam - anyone with an idea?

I'm purposely sticking away form Dynamat on principle (cost for what you get). I've got these guys who seem to have a well spec'd product at a great price - but haven't pulled the trigger yet...

Soundproofing Foams


Soundproofing Foams

 

I was thinking about doing this to my car once it arrived. Depending on the results from the foam that RROLFF posted, I may go that route instead since its probably much easier than laying the dynamatt style material.

 

Amazing job. Makes me want to do mine as well. WEll done mate. Can't believe you have the courage to strip out the entire car.

 

Don't want to pull your chain. You seem to know what you are talking about. However, so where are the crital locations that we should put the sound absorbers?

Again very easy said than done. So for people who are intrested in sound proofing their car (Prius 3) where should we put the materials so we don't overkill, being impractical and expensive?

I don't want louder music to drown the noise. I want less noise. Louder music means more noise to me. It is not a solution.

 

Think about what happens when you tap or rattle a really thin tin pan. Now imagine what happens if you glue a piece of foam in the center, then you tap it. The sound is muffled, even when you tap on the bare metal.

I'm sure that a genius could figure out exactly
where to apply dampening material, but it's likely that 50 or 60% coverage will go a long way. I'm dying to try this.

 

Well I am no genius. And if all centre are crital areas then I am sure just say centre and why say critial areas? So the floor of the car the centre is the centre of the car where the centre colum is?

What about the door? Just 50% of the middle? Hmm I am sure not going to listen to you even I know nothing of sound proofing. I have taken apart of really high end car doors before and they sure have sound proofing all over the door and not just in the middle.

Very scientific Einstein.

 

Thank you very much for the informative post and progress report!

I was wondering if you had a guide to removing the door panels and trunk panels? I just don't want to risk breaking any of the fragile plastic parts.

Thanks in advance!

 

Great post subject
Did the doors on my GMC pickup a few years ago with duramat, used a roller and really rolled it in, after a few years it separated and fell away from the metal and got tangled up in the window, had to remove it, then I had the truck oiled and looked in the doors, not a chance of reapplying now, oily residue great for retarding rust not so great for applying sound deadener...Had the Prius oiled last summer and hadn't added sound deadener to the doors yet, oops...Had done the floors and trunk area already.

Get out the hair dryer and roller and heat it up and roll it in or it will IMHO separate and clog.