Acapulco Bill

The entire video is laughable at best. No science behind placing a randomly sensitive uncalibrated cell phone on top of a vibrating surface - the armrest - which transmits substantial amounts of low frequency energy to the transducer of the "measuring device", with the microphone aimed at the mid and high frequency absorbing ceiling. No spectrum analysis provided. About as scientific as the video's use of randomly-sized boxes to compare luggage space.
Acoustic engineers take excessive care in both isolating the microphone from unwanted vibration and assuring that an omnidirectional (spherical) sonic sample is obtained for ambient acoustic surveys. Harman Kardon engineers spent millions of dollars profiling the interior of the BMW 3 Series and Mercedes C Class with a myriad of measuring instruments, to develop the digital signal processor data for the Logic7 system. The acoustic environment of any car's interior is extremely complex - concert halls and stadiums are simpler.
So have fun on Sunday. Or go for a 50 mph ride in a Maybach, Rolls Royce, or maybe even an EV like the Tesla, Prius or Chevy Bolt. The W204 is far from being "scarily quiet" (it's one of the noisier of 36 cars I have owned) and trying to justify otherwise with ill-gotten numbers serves little purpose. While most MBWorld users talk about making their rides LOUDER, best of success in achieving subjectively "added silence" in a W204. And use the very best measuring device at your disposal - your own ears.

superangrypenguin

Hi Bill,

I agree with some of your points, and disagree with some of yours. Of course, HK spent millions on profiling said 3 and C series! -undoubtedly, that's for sure.

The reality is that, and I've said this upthread, the best way for non-professionals like me to figure out noise levels is to use the same measuring device to test multiple cars that drive on the same road at the same speed in the same weather conditions. I don't give any weight to what the DBA is, but the only weight I do consider important info is relative speaking, where does each vehicle lie on the spectrum.

E.g. A C is quieter than a 3 series, but louder than a F150.

Now that said, if I had access to the decimeters that you are referring to, maybe I'd actually give weight to the information given to me. That said, maybe your ears are trained enough to figure out the difference between 67dba and 68dba, but for the vast majority of us plebeians cannot tell the difference, mainly because sound levels, as you know, are not linear. You can also see this all over the web, especially with tire reviews where some people (5%) will complain about tire noise, when 95% think the tire is spookily quiet. Human perception is often poor, and thus for the purposes of my testing, I'll still use some sort of meter, even if the only relevant info it'll give me is relative info.

It would be really awesome if I could even test the same car, driven at the same speed, on the same road in the same weather, with the same brand/make tire, because as we all know, comparing two cars with different tires isn't exactly fair, let alone a car running RFTs and a car without, but unfortunately I'm not inclined to ask a dealer to do this, let alone spend the sum of money to make that happen.

To me, the relevant info gleaned in that Youtube video upthread which can be applied here is that the 7, the S and the A8 are relatively the same, noise wise, provided that the reviewer took 30 second samples of said testing info while measured all on the armrest in the rear, provided he was driving on the same road (at the same speed, which it appears he did). So for me, my next test can be using my car vs an S class, on the same road at the same speed, and these outcomes can be determined.

W204 > S class [and 7 and A8]
or

W204 < S class [and 7 and A8]

or

W204 = S class [and 7 and A8]

because the S, as demonstrated by the reviewer is roughly as noisy as the 7/A8. Agree/disagree?

Also, I think you'd get a kick out of this. https://mbworld.org/forums/c-class-w...5-s-class.html

Compared my W204 (same phone, same app) to a W221 and W222. There are a few variables that I discuss here, but the results were surprising!

superangrypenguin

Oh hey, look what I found!

http://www.carmag.co.za/technical_po...hicles-tested/

So as I mentioned upthread, it isn't fair comparing my DBA readings with the one in the thread above, but I was surprised to find some further evidence backing up my DBA readings for the S550 in my other thread, here: https://mbworld.org/forums/c-class-w...5-s-class.html

Interestingly enough, the carmag link here showed the S63 at 71dba cruising at 120kmphr. Sure, these results have a bunch of variables to consider, but I found the info interesting nonetheless!

This one is also interesting:

http://elevatingsound.com/the-top-30...-by-auto-bild/

Note though, the only W204 they tested was the BlueEfficiency one, which isn't necessarily a fair test because BE cars have reduced soundproofing in order to save weight. Too bad they didn't test a W204 that was not a BE one! Still, made it to their top 30 list!

superangrypenguin

Interesting. Edmunds actually tests some of this, thus reducing some of the need for me to do this. Take a look here:

https://www.google.ca/url?sa=t&rct=j...DCuQozY8y5FUnd

level @ idle (dB)45.2
@ Full throttle (dB)72.3
@ 70 mph cruise (dB)61.8

versus say a 2011 E https://www.google.ca/url?sa=t&rct=j...DEjXVZHQ7ZWWpE

level @ idle (dB)46.6
@ Full throttle (dB)66.9
@ 70 mph cruise (dB)63.4

This one compares the S to the 7 to the XJ.

http://www.autoexpress.co.uk/bmw/7-s...s-vs-jaguar-xj

=========================================

Car and driver (2012 C vs BMW etc): https://s3.amazonaws.com/amv-prod-ca...ison-tests.pdf

Car and driver S class https://s3.amazonaws.com/amv-prod-ca...atic2018-1.pdf

Car and driver Lexus LS/Equus (2010) https://s3.amazonaws.com/amv-prod-ca...ndai-equus.pdf

This is basically proof the S class is the same noise level as the W204 at 70mph... surprisingly.

And just for fun: Maybach S600: https://s3.amazonaws.com/amv-prod-ca...chs5602018.pdf


*and holy moses the C450 W205 is noisy! https://s3.amazonaws.com/amv-prod-ca...nuary-2016.pdf

superangrypenguin

One last one from C&D:

https://s3.amazonaws.com/amv-prod-ca...t-for-38-3.pdf

Interesting. C300 (non DI) W204 at 70mph, 67db. Basically the same result as mine (my vehicle's result was 67db at 120km/hr, which is more than 112kmphr which is 70mph).

Acapulco Bill

Again suggest the free SPLMeter app for your Samsung, which has a decent 1/3 octave analyzer and hold modes. Then try and find a calibrated professional SPL meter and get the calibration within roughly 1 dB. Placement in the vehicle is important, because if you point the cell phone towards your face, a sound absorbing surface, the measure will be low by 3 - 5 dB. Best and safest way to take measurements is to have someone else along for the test, and point the cell microphone towards the front windshield about 12 to 15 inches away at ear level, as it is a reflective surface and directs the sound waves to your ears as you drive.
Reviewing your posts above, the Jaguar XJ is probably the quietest at about 62 dB (practically useless to try and measure 0.1 dB in a moving vehicle, ones breathing will change the measurement substantially). So using that as a reference, probably the W204 comes in close to 68 dB @ 50 mph and in the 72 - 75 dB range at 70 mph, of course the kind of road surface is the primary culprit of noise, concrete will be 3 - 6 dB noisier than smooth asphalt. Hope you can get trustable measurements.

Alfadude

Scarily????

W204Motorsports

Great info there, my car is just sitting right now since my bumper is at a body shop after a long and snowy winter ( Amg sport bumper makes for a nice plow).

Anyways, I found this video; and the foam looks like a mix of MLV and closed cell foam which is exactly what the w204 is missing. I used some second skin MLV mats but only in the back because it wa very expensive and I didn't get a lot of it, most of my money went into the vibration reducing sound deadener.

https://www.deadening.co.uk/pages/advice, this is the main recipe for sound deadening, with all 3 of those combine, you will achieve maybach level out sound proofing. Im going to home depot to pick up some of those rolls and see how much quiter I can get my car, I tested idling again with the windows closed and im at 36-37 DB with the SPL app, will see if the results change after the foam is installed.

superangrypenguin

Thanks Bill and ltwargssf


Very excited to say I found a spot today that I have confirmed reduces the noise by another 1db! This was my testing methodology.

Controlled environment with a very loud source outside of the car. Test #1 (without my new soundproofing idea/insert). Test #2, -1db or, at best, -another db. (Averaged to 1.5db reduction)!!!!

Same location and same device for the microphone to pick up the sound level. Really excited and can't wait to share. I just have a bit more testing to do tomorrow and then I'll share. A great $20 mod, and LOVING the result thus far

And itwagssf, just reviewing your Youtube video now and will give it a look and see if I can do it. If you can pls post results, I and others I'm sure would love to see the before and after!

superangrypenguin

@itwargssf, what are you buying at Home Depot? I didn't know they carry some of this stuff!

W204Motorsports

https://www.homedepot.ca/en/home/p.p...000749177.html

I just came back with this, im suprised how light it is,kinda happy about that because I must have over 80lbs already in my car lol. 75 sq feet sure is a lot and Il have enough to double or enough triple layer it in key areas. I plan on starting with the back of the fender splash guards and under the carpets, front and back, including every little exposed metal that mercedes didnt cover up.

superangrypenguin

Holy sh**, this is fantastic. I've read interesting things on the results of what you're doing. Some have said, HOLY CRIKEY big difference and some have said it's a waste of time. Obviously it's dependent on the car. I'm not so sure if you will get a fantastic result, but I suspect the variable here is how much tire noise you have now. I literally just put on a new set of tires (Primacy MXM4s) and they are already really quiet. My main battle is with wind noise right now. I'll tackle my front (shutting out wind noise from the A->B pillar area), and if you can please tackle your project and we can report back on results.

By the way, any idea what's a more effective sealer?

Closed cell foam touching a rubber OEM door seal, OR a D type door seal touching a rubber OEM door seal?

I did see this:
https://www.energy.gov/energysaver/w...atherstripping

Obviously, I'm going to be using a closed cell foam due to water concerns, but I'm not sure if I should be using closed cell foam weather stripping or if I should be using D type rubbers only to seal around doors. Thoughts anyone?

W204Motorsports

Weren't you using some kind of universal rubber stripping? The pictures you showed seemed to be rubber, after seeing those pictures I added this type of foam; (http://www.keepitquiet.co.uk/resilient-sealing-tape/) . I used it in the same spots you did, initially i only had it on the top weather stripping and behind the mirror, theres a triangular shaped rubber seal and I but that foam behind it too push it out and that fixed my wind noise coming from around the mirror.

After seeing you're pictures, I've since put it all around the doors, front and back of the door( next the the fender and back of the door just like you did. now I haven't tested all this, my car has been sitting disassemble for a few days so I can only get Idling results for now.



Now back to the point where people say it is useless, sound proofing has 3 key elements, you need to stop the vibration, absorb the sound and then deflect it, without all 3 you will not see great results. my car already has the vibration part done ( dyno mat), Mercedes does use a lot of foam so that is the absorber and now I will be putting the final touch with the eco roll from home depot with it being the barrier, I'm expecting good results honestly, I have some second skin MLV mats in the trunk which is a barrier like the roll I got but it was 5 times more expensive and I didn't have much of it. This roll I got from home depot isnt as thick but I have so much of it I can just double layer and it will be jsut as good as the expensive second skin mats I imagine.

superangrypenguin

So I've been going back and forth. At CDN Tire, you can get this: https://www.homedepot.ca/en/home/p.c...000113273.html in black, and I have been using it. I ripped most of it out though, and swapped it for this:


I'm not sure what is better, to be honest. My main thought/concern is for any part that touches metal, is closed cell weatherstripping a good idea? I know closed cell foam doesn't generally let water in, unlike open cell foam, but rubber itself (D ring rubber) holds 0 water since rubber doesn't absorb water.

So from a rust perspective (thinking worst case), I suspect using closed cell foam is not a good idea, because it may still trap some salt and water in the winter, and if that constantly touches a painted surface, maybe it'll rust?

In the pictures where I was putting in foam in the windowsill, well, that was closed cell foam. For my other photos sealing up the doors and such, that's the Amazon stuff above.

I'm just not sure what is better at blocking out sound. Sure, closed cell foam is better at absorbing sound, but I suspect rubber is a better deflector of sound? Too bad I can't use both...well, maybe I can, stick the foam in the rubber seal? Ok, maybe that's going a tad TAD bit too far

**Note, after extensive testing, the closed cell foam I was using wasn't making an effective seal as it wasn't thick enough, hence ditching it and going with the rubber D ring seal instead.

superangrypenguin

PS I almost missed this. Thanks for the tip!!!

W204Motorsports

haha yeh that would take some time inserting the foam in the rubber seal. I wouldn't be too worried about rust because the foam will probably deteriorate well before the paint gets any rust on it. With it just being a strip, I dont think its makes any difference what blocks of the most noise, if the rubber or the foam are both pressed in and compressed, they equally block the air and sound trying to get in because its such a small area. I imagine the thickness one that you can fit in there without making the door hard to close will be the best.

Im looking into the rubber strips and there's many different sizes, which one did you get ? I think im going to order the 12mm.

superangrypenguin

Very good points. Thanks!

I'm using the little D one in the Amazon link upthread. It's one cm wide and 8mm high iirc. It's doing a great job right now. Have more on order. Have used about 16 meters, yes meters so far.

superangrypenguin

I have an interesting question.

So where the hood touches the front fenders on both sides, there's about a 7mm gap. Is it worth sealing that off or is that used for heat dissipation for the engine?

W204Motorsports

lol, I tried to put my foam there but it didn't stick and wasn't thick enough anyway, I too am curious if it would affect the engine bay temperatures. I will put the 12mm rubber seal there and if it does reduce noise, I will test engine bay temperatures with my digital thermometer and see if it affects it.

superangrypenguin

Thanks. I was just going to go and buy one of those infrared digital thermometers so you saved me some money

PS - I couldn't find any reference anywhere for either OEM (I doubt it) or aftermarket (surprised that I didn't find any) acoustic glass and/or windshield. That would have been my next move, but I don't see any. Have you or others come across them?

W204Motorsports

We gotta give these guys a call, a fully armored and bullitt proof mercedes should be really really quiet inside.

superangrypenguin

BAHAHAHAH!! YES!!

superangrypenguin

Ok ladies and gentlemen, my project (for now) is complete, and I'm pleased to share the results.

Note: My primary goal with this experiment was to ensure that the testing methodology, if followed by someone else, can be reproducible. This was really important to me.

Vehicle tested: 2012 C300 4matic
Tires: Primacy MXM4. 29psi front, 34 psi rear. Please note: on my vehicle, I hear 0 road noise, 0 tire noise. Most of the noise generated by my vehicle that is audible to me is wind noise.
Road: Highway 407, far west end of the 407 to Highway 403 exit. Asphalt only. Those of you who live in Ontario know most of the 407 is concrete and noisy, I ensured that testing was done on asphalt as most of the 400 series highways are asphalt, and on the 407, there are very few expansion joints and fillers in the road, so testing was consistent.
Weather: Between 0-8'C, dry, sunny

Results: ALL measurements taken below: For each run, I focused on getting the lowest DB possible. This usually meant the road was either level or a slight decline causing the engine to work less hard. EVERY single measurement below was taken after multiple attempts to get the lowest DB number possible. I experimented with how best to capture the sound - phone free hand near the center to try and minimize effects by expansion joints, or mounted to a mount. The latter turned out to be more predictable, so all measurements below are captured when the phone is in a mounted position, and the same position every single time. While this does not completely isolate the phone from road noise, etc, it's a pretty accurate measurement as all measurements were taken at the same location.

Control (stock):

60kmph: 60db
80kmph: 62-63db
112 kmph/90mph: 67db
120 kmph: 67db
130 kmph: 70db
140 kmph: 71db
150 km/hr: 72db

Results after modification:
60: 58db
80: 61db
112 kmph/70mph: 66-67db
120 kmph: 67-68 db
130 kmph: 68-69db
140 kmph: 71db
150 km/hr: 72/72/71db

General observations:Success was mixed. Generally speaking, below 140km/hr, there is a noticeable (by ear) difference that is corroborated by decimeter findings. It seems that as one drives faster and faster that there is diminishing returns. Eg There must be so much wind noise/friction generated by the vehicular movement that the db improvements become less and less. That said, qualitatively it would appear that when there is significant cross wind (e.g. a gust of wind) that the vehicle, post modification, is quieter. That said, there is an improvement at speeds <=130km/hr.

Conclusion: For the $40 or so worth of rubber seals I bought, it was totally worth it. This experiment was also really fun to do.

Next steps: I'll be visiting my MB dealership shortly (appointment got pushed out). I will be taking a CLA250 (loaner) and a S450/560 (test drive) on the same piece of road and taking measurements again. It'll be interesting what I find, db wise, in those other cars. I don't think I have any immediate plans to continue my project on my car, but will be looking at the results that ltwargssf as he/she is working on combating road noise/tire noise. That concludes my part of the test

What I find most interesting is that the S550s and such, when testing by Car and Driver, only show results up to 70mph. I think it'll be up to me/us to test these vehicles near the 150kmhr range...

Happy testing and please share your results and ideas!

superangrypenguin

W205: Just came across this. Found it interesting: http://alexonautos.com/cabin-noise/

W204: http://www.thetruthaboutcars.com/2009/02/the-art-ofnoise/ <--very neat. This result is basically giving me the same info as above. 68db at 130km/hr, and since it's already one of the quietest cars in that list, I think I'm done my project... lol.

W204Motorsports

Updates are coming, I was away on vacation and I still have a few things to put back together, impressive results you got there, cant wait to test mine out.