Canopy Makes it Loud!

[JohnS]

If noise is being generated by the metal canopy resonating, the asphalt panels will do a much better job of damping the panel. Acoustic foam will handle reflected noise better then the asphalt. Best solution would be the layer of asphalt, then the acoustic foam.

JohnS

 

[PaulinSD]

I needed a sun shade for our JD 1050, and built one with 1 x 2" steel tube frame with 14 gauge sheet metal for the shade. Extremly loud from reflecting tractor noise and sheet metal ratteling. I removed the 14 gauge sheet metal, and my wife made a dark green fabric cover for the frame. Works great!! Just as quite as before, without the shade.

Paul

 

[JohnS]

Sounds like that just the ticket, for you. Pun intended! /w3tcompact/icons/smile.gif Sunshades in my area have very little work to do. It is more of a rain shade. /w3tcompact/icons/wink.gif Also makes for a good place to mount aux lights and other things.

JohnS

 

[patrickg]

John, the asphalt and acoustic layers together is a good idea. Attach the asphalt to the top first then the lighter material, just in case the order wasn't clear before. I don't know how much head room you have in there but egg cartons (I've never used the plastic ones) make a good sound reduction surface. The layers of formed paper/cardbord that go between layers of eggs in the LARGE egg crates are better than having to use the one doz size. If there is room I would consider a layer of the egg crate (not egg crate shaped matress topper stuff but REAL egg crate) between the asphalt and lighter acoustic material.

One day we (as a group) should look at tractor noise at the source. Noisy mufflers, location of exhaust and direction of its exit. When I say noisy mufflers I don't mean "glass packs by Cherry Bomb Inc." Mufflers radiate noise out their surfaces. Wraping a muffler with refractory type cloth material and making a sheet metal cover for it will reduce the noise by a considerable amount if the muffler was much of a radiator as many are. If you can see the exit opening of your exhaust from anywhere under the canopy then perhaps you should conlsider a small extension to direct it elsewhere.

Sound waves coming from the exhaust outlet (as well as all other tractor generated noise) that used to stream past you may be caught and reflected to you by the canopy. Trying to dampen their reflection at the canopy's inner surface is a good idea as part of the solution. If there is a direct radiation path from the exhaust outlet to the underside of the canopy then redirecting the outlet, a pretty trivial task usually, would sure help as a part of the solution.

There is some hi-tech sound reduction called (I hope I get the spelling close) Barryfoil. They produce various sound reduction materials. Some are lead loaded foam (lead dust in the foam matrix) with very high coeficients of extinction. Some of their materials have a thin lead sheet between two layers of foam. This last type is to stop sound penetration and would be placed as linings to engine covers and like that, not on the underside of the canopy.

The active noise canceling headsets are a real good idea as well, especially if you want to use a two way radio or listen to tunes or whatever while tractoring. Not cheap, but I think I will get a set 'cause they are so good.

Patrick

 

[Hillbilly]

I always wear ear plugs when I drive the tractor and run my chainsaw,or target practice. I use the soft foam kind you can squeeze with your fingers and insert slightly in your ear canal.I got in the habit of using them because of my job.The only problem is I would not be able to hear a radio if I had one while wearing these./w3tcompact/icons/smile.gif

 

[patrickg]

Hillbilly AKA Mountain William, I use those squeezable foam jobbers too. I like them better than the custom form fited ones I used to get at the lab. They are pretty comfortable, effective, inexpensive and you can run them through the washer and dryer and get them back in good condition A N D real clean. I always get mine dirty from my "mechanic's hands".

Actually, if you have good speakers and enough power you can listen to the radio just fine with those in place AM/FM or 2 way. Been there, done that. If you don't want complaints that your tunes are louder than your tractor, get a set of ear phones that will play loud enough to get thru the plugs. Been there and done that too. For not too much more $ than a set of ear phones to blast thru the plugs you can get phones that exclude the outside noise pretty good and let you hear the tunes even better.

It is an extravagance but sometimes I spend a lot of time on the tractor in a stretch. (anything over 6-7 hrs on a tractor is a LOOOONG time to me) so I will probably bite the bullet and get the active noise cancelling ear phones. In my professional opinion, they are seriously overpriced based on cost to design, produce, and market but remain a bargain when consideration is given to what they do for you.

Patrick (waiting for the world to start back up on Monday)

 

[JohnS]

Patrick,

You bring-up some very good points. Since, my tractor will go into hybernation at the end of Novemeber, I am planning some tests for next year. I have acoustic foam and a Rat Shack DB meter to determine if it makes any difference. I have other PC analyzer S/W, but would have add another 25' of coax cable for the mics and preamps, to reach outside. /w3tcompact/icons/smile.gif I can also look into some of the exhaust options. Anyone here ever convert their tractor from a normal exhaust stack, to one that goes under the tractor? Which appeared to be louder?


JohnS

 

[patrickg]

John, Thanks for your kind words. Consider my acoustic advice a belated tax refund. It seems many (but not all) of my years of schooling were at the taxpayer's expense. As I recall, I paid for the upper division acoustics (physics) but no matter, its free on TBN. Sort of my personal swords to plowshares sort of thingy.

An alternative I did not mention is similar to the active noise cancelling headsets. Install the equivalent of a grid of active noise cancelling headsets but using small planar speakers to "tile" the underside of your canopy. It makes it into essentially a noise transparent surface or complete absorber whichever way of thinking works best for you. Each element in the finite element approximation of continuous surface is moved by its voice coil so as to generate an acoustic waveform equal in magnitude and opposite in phase to the incident sound. The equal but opposite wave adds through algebraic superpositioning to the incident wave and cancells it out. This does work but it might be cheaper to send a kid to an orthodontist for several procedures.

Oh, by the way, this array or matrix of transducers can be fed with your programmed music source and can simultaneously be left, right, center, and sub base speaker systems. One downside is that it will not discriminate between sound sources so it will also try to cancell a portion of your wife's plaintive cry to come wash the dishes or the sirens on the emergency vehicle that wants to pass you on the highway.

Patrick

 

[Alan L.]

My canopy is a very tough Orange poly/plastic of some sort. My son is bringing me some of that foam egg crate stuff they put in speakers. The only have purple, so the purple/orange combination might be interesting. I might velcro it up there until I decide thats the answer, then I'll glue it. The stuff ain't cheap however - about $16 for each 2 X 4 sheet.

Alan L., TX

 

[JohnS]

Patrick,

We might just be over complicating the solution, just a tad! /w3tcompact/icons/smile.gif

I remember reading about active sound cancellation, some time ago. A number of toll boths tried them. Don't know if they still use them. I do remember something about disoriention of the operaters. Something about not cancelling completly and messing with some of the millisecond timing that our brain reacts to.

If the low-tech sound deading doesn't work, I will just use a headset ear muffs. Easy to put a hook holder on the canopy to store them on. /w3tcompact/icons/wink.gif


JohnS