B2320 - an experiment in sound deadening

PhilVA · Sep 7, 2014

So I've had my B2320 w/ canopy for a little while now and am really enjoying mowing the pastures and yard with this thing. I noted that although a little quieter than my L3000DT it still makes a good bit of noise. When operating any machinery that generates a good bit of noise I always wear my USN "Mickey Mouse ears".

I wondered how much noise the little beast put out (and if I could diminish it some) so I downloaded two decibel meter apps (for comparison of readings) for my smartphone. I bought some cheap "egg-crate" foam mattress pad from WalMart to act as the sound dampening material for the underside of the canopy, thinking it would behave like the stuff you see lining the walls in an anechoic chamber and absorb the sound bouncing off the canopy.. I placed my smartphone near where my ears would be to get the sound samples and ran each app to check the sound levels. Here's the result of the individual tests (completely unscientific):

Tractor without canopy (idle) - 82dB
Tractor without canopy (2500 rpm and mower running) - 84dB

Tractor with canopy (idle) - 83dB
Tractor with canopy (2500 rpm and mower running) - 85dB

Tractor with canopy & "egg-crate sound dampening (idle) - 81dB
Tractor with canopy & "egg-crate sound dampening (2500 rpm and mower running) - 83dB

While not as great a dampening factor as I had hoped, it did make a difference. Although 2dB's is not significant (with canopy), I think having the canopy protection from the elements outweighs the slight increase in noise being reflected off of it and back to the operator. I'll still wear my "mickey mouse ears" to protect my hearing. Most people cannot perceive a 3dB difference in sound (from what I've read).

For reference to some various noise levels, here's a chart of the most common:

Weakest sound heard 0dB
Whisper Quiet Library at 6' 30dB
Normal conversation at 3' 60-65dB
Telephone dial tone 80dB
City Traffic (inside car) 85dB
Train whistle at 500', Truck Traffic 90dB
Jackhammer at 50' 95dB
Subway train at 200' 95dB
Level at which sustained exposure may result in hearing loss 90 - 95dB

mswlogo · Sep 7, 2014

I have a pair of Bose Sound Reduction headphones that work very good.

However they are a bit risky operating the tractor so I have not used them too much.

I just picked up a pair of these since I play fiddle and it can be a LOT louder than tractor. I measured 104dB on my left ear.

Etymotic Research, Inc. - Music

These work amazingly good. I can't wait to try them on the tractor.

bp fick · Sep 7, 2014

Chain saw operation, running the splitter, target practice and running the tractor. I just use my Husqvarna ear muffs.

mikehaugen · Sep 7, 2014

PhilVA said:
Tractor without canopy (idle) - 82dB
Tractor without canopy (2500 rpm and mower running) - 84dB

Tractor with canopy & "egg-crate sound dampening (idle) - 81dB
Tractor with canopy & "egg-crate sound dampening (2500 rpm and mower running) - 83dB

It actually made the tractor quieter than without the canopy, that's surprising. I would call it a success.

Pepsiboy · Sep 7, 2014

PhilVA said:
So I've had my B2320 w/ canopy for a little while now and am really enjoying mowing the pastures and yard with this thing. I noted that although a little quieter than my L3000DT it still makes a good bit of noise. When operating any machinery that generates a good bit of noise I always wear my USN "Mickey Mouse ears".
View attachment 389439

I wondered how much noise the little beast put out (and if I could diminish it some) so I downloaded two decibel meter apps (for comparison of readings) for my smartphone. I bought some cheap "egg-crate" foam mattress pad from WalMart to act as the sound dampening material for the underside of the canopy, thinking it would behave like the stuff you see lining the walls in an anechoic chamber and absorb the sound bouncing off the canopy.. I placed my smartphone near where my ears would be to get the sound samples and ran each app to check the sound levels. Here's the result of the individual tests (completely unscientific):

Tractor without canopy (idle) - 82dB
Tractor without canopy (2500 rpm and mower running) - 84dB

Tractor with canopy (idle) - 83dB
Tractor with canopy (2500 rpm and mower running) - 85dB

Tractor with canopy & "egg-crate sound dampening (idle) - 81dB
Tractor with canopy & "egg-crate sound dampening (2500 rpm and mower running) - 83dB

While not as great a dampening factor as I had hoped, it did make a difference. Although 2dB's is not significant (with canopy), I think having the canopy protection from the elements outweighs the slight increase in noise being reflected off of it and back to the operator. I'll still wear my "mickey mouse ears" to protect my hearing. Most people cannot perceive a 3dB difference in sound (from what I've read).

For reference to some various noise levels, here's a chart of the most common:

Weakest sound heard 0dB
Whisper Quiet Library at 6' 30dB
Normal conversation at 3' 60-65dB
Telephone dial tone 80dB
City Traffic (inside car) 85dB
Train whistle at 500', Truck Traffic 90dB
Jackhammer at 50' 95dB
Subway train at 200' 95dB
Level at which sustained exposure may result in hearing loss 90 - 95dB

HEY ! ! ! Nothing wrong with "Mickey Mouse" ears. I wear them, also. I was amazed at how much 'equipment sounds' I could hear WITH them compared to WITHOUT them. Little things like the whine of the hydraulic pumps and motors, and the clicks of the tiller hitting small rocks (under 1 1/2 inches). The ears might look funky to some people, but if they SAVE YOUR HEARING, who cares???:cool2::2cents:

Dave

dougtrr2 · Sep 8, 2014

Pepsiboy said:
HEY ! ! ! Nothing wrong with "Mickey Mouse" ears. I wear them, also. I was amazed at how much 'equipment sounds' I could hear WITH them compared to WITHOUT them. Little things like the whine of the hydraulic pumps and motors, and the clicks of the tiller hitting small rocks (under 1 1/2 inches). The ears might look funky to some people, but if they SAVE YOUR HEARING, who cares???:cool2::2cents:

Dave

I also wear ear muffs when on my tractor or using chainsaws and splitters. I also bought child size for the grandkids. One daughter refers to them as her "ear puffs"

Doug in SW IA

Pepsiboy · Sep 8, 2014

Doug,

That's cute ! ! !:laughing:

Dave

PILOON · Sep 8, 2014

I have had a bit of experience with soundproofing aircraft.

First there are different types of 'noise'. Vibration being one, engine another and then the high pitched noise like in propellers and turbines.
Most if not all vibration related which are amplified by large surfaces are the easiest to control. Like in cars, felt works well but I also learned that roof self adhesive membranes stuck to the large surfaces work very well.
To isolate engine noises sticking some (non absorbent) material to the underside of the hood and the engine side of the firewall will help a whole lot as well.
The Bell Jet Ranger (206) used a 3M dense foam product that was 1/4" thick, self adhesive and had a few mills of lead facing that was super effective in reducing sound. I did the firewall of my Cessna and 6" strips on most of the engine cowlings with the material and could then carry on conversations in a normal voice. So effective that I could then hear the valve tappets clatter.
Some earlier A/C actually had strips of tar paper stuck to an large panels to cut down vibration generated noise. (drumming)

I have treated my home made tractor cab in this manner with great results.

Bagged house insulation stuffed into nooks and crannies is also effective. (bagged to keep out oils and water)