2nd Gen Non-Engine/Transmission Measured '02 noise levels...

[Gary - K7GLD]

Since there is some interest in relative noise levels generated by our trucks, I decided to take some sample readings in and around my own truck...



A few specifics, my truck is a '02 quad-cab ETH/DEE with 7000 miles on it - no mods other than the listed COMP - certainly nothing that would affect noise levels. The meter used will be seen to be a Radio Shack decible meter - this one was checked and verified against the standard used by a local area lab that does industrial testing of workers in high noise level environments. All exterior samples I took were at a measured distance of 3 feet - distance is pretty critical - a mere couple of feet can make a significant difference in readings.



Also worth noting are meter ranges and settings used - I used "C" weighting that gave the HIGHEST DB readings, since it's sensitive to a wider range of audible frequencies, and a response time that reacted most quickly to changing audio levels - as an example, on the setting I used, random ambient noise level out at my country location displayed 55 DB in what is VERY quiet surroundings - using a more "generous" range "A" showed NO DB level at all for ambient noise, since the frequency response for that range is limited, and dropped the interior noise level of my idling truck down to an indicated 62 DB - I prefer the ranges I selected - they might not be as impressively low as possible, but I feel they're more accurate and honest, since the range of audible frequencies the Cummins and related hardware/road noise generates is pretty wide ... Here's the setup for exterior readings:

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The DB reading at that setup was 85 DB - the same as seen from the front and rear center of the truck at 3 feet - the highest exterior reading was at the left front side of the engine area:

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The reading taken right in the engine bay on the driver's side, with the meter sitting on top of the fuse/relay box and pointing toward the engine:

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From inside the truck, sitting still at engine idle, and all windows closed, meter sitting on center console/armrest right in the middle, and pointed at the dash:

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That's 75 DB in case you can't see it clearly - for reference, 75 DB is about the equivelent DB level of normal speech taken at about 12 inches...



Down the road, at 50 mph on a reasonably smooth country road, coasting with engine running, I was seeing 83 DB - which went to 84-85 DB in O/D at 50 mph - the increase was all the rumble of the exhaust, no engine noise was present that *I* could hear.



So there ya go - be interesting to see similar readings others might provide, either after noise-reduction mods, or perhaps with straight pipes and maximum loudness!

 

[Wiredawg]

Gary:



Very interesting info! I know when I'm running down the road with the radio on and come to a redlight, I have to turn the radio down. This means I have to turn the radio up to be able to hear the it over the engine/exhaust when running down the road. I like it!



I'm gonna buy my wife an 03 3500 SRW HO with the 48RE transmission. I reckon I'll have to replace the stock muffler with a Walker so we can hear her truck.



Take care, Wiredawg

 

[klenger]

It looks like my generator meets the national park standards, but my truck doesn't. I guess I can camp there, but I'll have to pull the 5er in by hand.

 

[RBSOB]

Great work Gary. Thanks for all the effort and detail. I'd love to see a comparison to a stock '03 with the same meter/same parameters. Are they really "much quieter"? Jim G.

 

[wlowe]

Gary, Gary, Gary, You have entirely too much time on your hands, (not a bad thing to have too much of). But I will say that I find your efforts very informative, keep up the good work. It would be interesting to see what the '03 numbers are.



Thanks,

Bill

 

[krs]

Gary,



Why not go back out and get some real life numbers? It appears that you hand picked ideal conditions. "Down the road, at 50 mph on a reasonably smooth country road, coasting with engine running, I was seeing 83 DB - which went to 84-85 DB in O/D at 50 mph"? Well, GEE! and is that the normal over the road ambience you experience? Coasting at 50 on a smooth road?



Maybe if you'd climbed a hill and reported that, or hooked up your trailer and took readings while pulling away from stoplights, or had even one report of the sound level while accelerating your efforts could be called a beginning of a thorough analysis.

 

[JWhitcomb]

Where can I find a list on the net that gives levels for everyday things. I need to get an idea of the db levels of things I encounter daily. Then I can get an idea what the numbers mean to me.

 

[Gary - K7GLD]

The whole purpose of my effort was to establish a few real-life baseline numbers for useful comparison - NOT to cover all remote possibilities







Thanks for the comments...

 

[Adam]

Gary,



Ya can't please everybody all the time. I, for one, appreciate the effort and time you've put forth to gather the info and share it with the rest of us. If someone else wants something different, let them do it. Unless of course, they try asking nicely... (I'd still say "No", but I'm like that sometimes )



-Adam

 

[wlowe]

Gary,



Again, thanks for the time and effort! I also thought your K&N Filter test was very informative. Sharing info to make our trucks better, thats what its all about.



Bill

 

[Gary - K7GLD]

One thing of interest out of the readings posted above, was the DB reading while coasting at 50 mph on an average road surface - the reading of 83 DB *seemed* to be pure road noise - tires, wind, etc. , - no discernable engine noise I could detect. That only increased by about 2-3 DB when the engine was engaged - and THAT increase was mostly - if not entirely - from the exhaust note!



If that is remotely accurate, at least for down-the-road noise reduction related to engine generated sound levels, a better muffler MIGHT produce the most immediate, noticeable results!



After that, whatever could be done to address wind and other road noises would help - and the sound-proofing efforts some members have done probably become effective there, as well in the situations where the truck is moving slowly or not at all, and the engine noise itself begins manifesting its presence...



And yes, there WOULD be situations, such as heavy accelleration with heavy loads that reveal additional sound levels - but it's not real practical to attempt to cover and present ALL those varied possibilities, we ALL have occasions where we are at a standstill with engine idling - and traveling down the road at moderate speeds - we DON'T all pull heavy loads up steep grades, so my efforts were aimed at mainstream, COMMONLY duplicated and reproduceable situations!



I'm retired and have lotsa time - but not THAT much time, or interest, on this particular subject...

 

[Lsfarm]

The Noise Nazi's readings

Well I duplicated Gary's test situations as best I could. The ground is frozen here, so I had no grass to park over, so I had to settle for my snow covered lawn. Reflected sound is a big factor.



The cold also had some interesting effects on my readings, since I keep my truck in my heated shop [about 45*f] the truck was warm when I took the first readings, but the engine was not up to temp. Then as the engine warmed up, the truck was cooling off [ambient temp 8* this morning].



So I had slightly higher readings than listed below at first, then they went down, then up again as the truck metal and insulation got down to ambient temps.



The 50 mph reading is a pretty good measure of base background sound, it has little if any wind noise in the reading, and not much road/tire noise.



Last summer I kept trying to get consistent 70 mph readings, but found that headwind to tailwind readings varied by up to 6 Db, and a slight hill was hard to guage. This is kind of like dyno readings, you need to keep an eye on the change in readings, and not focus on the absolute reading. Every dyno is different, and every truck is different. Gary's readings sound about right from the readings I've taken on other trucks.



My results [ sorry no photos ]



Wheel well readings at 3' 77 db left, 76Db right

Engine reading from top of fuse box:91Db

Idle in neutral in cab reading, meter on armrest: 70-71Db

Coasting at 50 mph: 78-79Db

In OD, holding steady at 50 mph, level ground: 80-82 Db. [4" exhaust]

And at 85mph level ground steady speed: 84Db.



Just for a reference if you put the ventilation on dash vent, and turn the fan on high with the engine off, the reading is 78Db.

I have been told that the Db scale is a logrithmic scale, and that a 3 Db reduction is about a 50% reduction in sound pressure. I'm not a mathmatics whiz, so correct me if I'm wrong.



This seems about right from my experience of going from my truck to an uninsulated one then back into mine. While mine is far from silent, it does seem about half as loud/painfull.



All these readings were taken on the 'C' scale, which as Gary described gives a higher reading than the 'A' scale. The 'A' scale is supposed to simulate our ear, and the 'C' scale is more a 'technical reading'. This doesn't matter, just as long as we use the same scale. There is another recent thread on Db readings, and they appear to be from the 'A' scale.



Sorry for the long post, and I'm sure the '03 will have most readings yet another 3-5Db lower than my readings. Maybe more??



Greg L The Noise Nazi

 

[Gary - K7GLD]

AH! GREAT info Greg!



Those comparison readings are VERY helpful and educational - and thanks for the extra effort - especially in duplicating distances and meter settings! Helps keep us all on the same page...

 

[HC]

Gary,

Thanks for the information.

 

[Diesel Freak]

way back when I had a straight pipe, we tested it at work. I blipped the throttle up to 1600 RPM, and the db meter read 117db as the guy holding it was running away!

 

[Pit Bull]

Gary, I think Kshine is one of the members that is trying to make his Cummins quiet, or at least make the cabin of the truck quiet so you don't hear the roar of the mighty Cummins . To each his own. I bought it because it was loud, would not change a thing, but that's me and we all have a right to make our trucks do, sound, and act the way we want :-{} . By the way Gary thanks for your efforts on this. Very interesting. I also would like to know what other everyday sounds (db levels) are for comparison. If anyone knows please post.

 

[Wiredawg]

My commentary on this thread....

Please take this as me being an active TDR member who trolls the TDR website regularly and who really enjoys the good info, clever dialogue and overall great commeraderie of the club. I've sat by watching this post take a disturbing turn. Gary presented some info he took time out to put together. When I read it, I took into account the conditions he tested and thought it was good info. As you can read from my previous post, I mentioned how noisy (a good thing) mine is. I never read into what Gary presented as being slanted, narrow or in any way being absolute. It was just good info to put in my back pocket.



What Gary did is what this site is all about: Presenting and sharing experience and information to the TDR membership in a frindly forum. I believe we should be careful about how we express our opinions here that we don't insult or belittle each other. There are really better ways to add to or give a different opinion without going to a personal level.



Finally, I enjoy the posts and learn lots from this forum. Lets all actively work together to keep it a friendly and informative place for Dodge/Cummins truck lovers to meet.



Wiredawg

 

[Pit Bull]

Wiredawg, very nicely put

 

[FDziurda]

1999 Noise Levels

I have the ATP wraps on my oil pan, valve cover, exhaust manifold and downpipe. I made the following measurements with one of the older Radio Shack analog sound pressure level meters FWIW:



C Msg Setting

Inside cab @ idle 73dB

LH Wheel Well @3' 83dB

RH Wheel Well @ 3' 81 dB

Under hood at Fuse Block 94 dB

50 mph coasting 84dB (Road Noise)

50 mph in OD 84dB (Road Noise)



The ATP wraps make a noticeable improvement, however, I can't quantify the amount, since I didn't make any measurements before installing them.





Frank

 

[illflem]

Originally posted by JWhitcomb

Where can I find a list on the net that gives levels for everyday things. I need to get an idea of the db levels of things I encounter daily. Then I can get an idea what the numbers mean to me.

Try here http://www.rcaanews.org/noiselev.htm