Why are chainsaws so loud?
There are essentially three moving parts of the chainsaw that together create the distinctive sound. Primarily the exhaust is the major player followed by the chain and then the teeth moving through the wood. Altogether the ear of the operator is overloaded with noise that can spill over to dangerous levels.
Let’s have a look at what makes a noise move from merely irritating to downright dangerous. The critical factor is the distance from the sound source to the ear of the listener and here the chainsaw excels. It’s close.
To your neighbor, the sound of you diligently trimming away in your garden is irritating, but to your ears, it is deafening because you are inches away from the exhaust.
Technically it is the ‘Inverse square rule’ that dictates the relationship between distance from the source and intensity. (The intensity drops by 6dB every time the distance between the source and the listener is doubled.)
How do I make my chainsaw quieter?
Is it possible to modify the exhaust system to make it less noisy without reducing the efficiency of the engine? Well, the simple answer is that one of the major factors affecting the performance of the engine is the flow of gas through the exhaust.
Too little or too much back pressure results in the performance of the engine deteriorating. While stories about poachers (and I’m not sure if one can poach a tree) feeding the exhaust gasses through a bucket of water to banket the sound, I have never seen it done.
The manufacturers have designed their products with the primary aim of producing the maximum power from the engine and consequently, power always trumps noise levels on chainsaws.
So, it is not possible to add additional material to the exhaust to muffle the sound any further.
Added to this the only control you have over the noise of the chain is to make sure that it runs freely and is well lubricated and keeping the revolutions down. The sound of the teeth moving through the wood is a minor concern.
Create a barrier between you and the noise
Modern chainsaws are sold with both a maintenance kit and some of the protective gear required for the safe operation of the chainsaw. Normally a helmet, visor, and earmuffs (Amazon link) are supplied with the saw so there is little excuse not to use them.
Chainsaws emit noise through a wide range of frequencies and earmuffs are better at absorbing sound at the high frequency levels whereas earplugs are more efficient at the lower frequencies.
Used together they will reduce the noise level to one that will not injure your ears.
Mufflers also have a rating that is important to understand. The ‘attenuation rating’ of the muffler is calculated by subtracting 85 from the anticipated maximum noise level.
So, for the safe operation of a chainsaw producing say 110 dB the Attenuation Rating of appropriate mufflers would be 25.
Mufflers also have a limited lifespan and as the firmness of the cushioning deteriorates so does the efficiency of the muffler.
They are inexpensive and it really makes little sense in keeping mufflers when the padding has deteriorated along with the efficiency of the sound absorption.
Use an electric chainsaw instead
Modern battery powered electric saws are powerful and can be operated for longer periods of time. They provide a viable alternative to the traditional gas powered machine and are suitable for most of the lighter range of operations.
So, to avoid seriously upsetting your neighbors when you set out to do a spot of pruning on a Sunday morning switch on the electric chainsaw, and not only will you be saving your hearing but also your relationship with the neighborhood.
What is considered a safe level of sound for your ears?
According to the United States Department of Agriculture and Forestry safe levels of noise are rated under seventy-five dB while exposure to prolonged periods of noise at levels greater than eighty-five dBA can damage your hearing irreparably.
A chainsaw working will produce around 120 dB of noise which is about the same as an ambulance siren and only ten dB less than a Jackhammer.
We are up there in the big league of noise levels and this makes ear protection essential if you want to avoid serious injury to your hearing.
There are two elements to the danger of loud noise: the actual level of the noise and the duration of it.
How long is safe?
So, a couple of minutes trimming away a fallen branch is not going to present too much of a problem but then again why take the chance when protective gear is so readily available.?
According to the United States Department of Agriculture and Forestry sound around the high eighty’s dB will damage your ears after two hours but go up another ten to twelve decibels and you are placing your hearing at risk after fifteen minutes.
As a rule, every 3dB increase in the sound level above eighty-five dB halves the safe exposure time.
For future use
Hearing is a one-way street. Once it is gone there is no magic potion that will bring it back so those precious few minutes that it takes to put on the correct ear protection are vital in keeping you in tune with the world around you. Be safe.