I have a theory about loud tools
being fatiguing. And that sometimes accidents happen because a tool is so loud
that people hurry to finish a cut or some other operation and make a mistake
that they probably wouldn't ordinarily make. But that's a discussion for
another time.
Today I wanted to touch on another problem that takes longer to show up:
hearing loss. It's what's called an "invisible injury." When I'm in
the shop I'm more concerned with keeping all my fingers and eyesight. But
hearing loss can occur if your ears aren't protected.
Loss can occur regardless of the amount of time your ears are exposed to high
noise levels -- even if only for a few seconds. Hearing loss is cumulative. A
little exposure to very loud noises here and there adds up. And over a
lifetime, even a few hours a week in a home shop can lead to some type of
permanent loss.
After thinking about this, the guys at Woodsmith magazine
contacted OSHA. OSHA considers noise levels below 85 decibels (dB) to be safe.
Anyone experiencing noise levels over 85 dB for any length of time
should use some type of hearing protection.
So we got to wondering how much noise is created in the Woodsmith shop. We
purchased a sound level meter to check. We expected the thickness planer and
the radial arm saw to register the loudest noise. When cutting a piece of
6" wide hard maple each produced a noise level around 105 dB.
But we were surprised with the other tools. When routing an 1/8"-wide
groove on our enclosed base router table, we got a reading of 103 dB with the
doors closed. With the doors open, it registered 106 dB.
The table saw registered 104 dB.
The biggest surprise was the hand-held circular saw. It put out a whopping 110
dB while cutting 3/4"-thick plywood.
The only tools that didn't put out a dangerous level were the edge jointer,
band saw, and drill press. (Actually, the shop toilet turned out to be pretty
safe too -- only 80 dB.)
So what can you do? There are a number of protectors available to guard your
hearing. Some go in your ears, some go over your ears. Most have a noise
reduction rating (NRR) from about 21 dB to 33 dB. Using a protector with an NRR
of 25 brings everything in our shop down to a safe level.
Some guys like the foam ear plugs because they're inexpensive and they don't
get in the way of their glasses. I like the "earmuff" style. They're
inexpensive and pretty comfortable. I often forget I have them on.
Which one should you use? Whichever one is the most comfortable (so you'll
actually use it).
Follow-up comments from readers originally sent out with Tip #45:
Two weeks ago I wrote about noise levels in the shop. That tip appeared to hit
a chord with many of you.
Robert Thomas said, "I suffer from a condition known as Tinnitus. It's a
constant ringing in one's ears (never will stop the rest of my life). With me,
it's both ears. This was caused by not caring from a young age about what I
exposed my ears to. As you stated, it only takes its toll over many years and
chips and chips away till one day you've lost much and can never get it back. I
only hope your readers are not as hard-headed as I was."
Bob Taylor also has Tinnitus. "I wish someone would have posted this
message 20 years ago. My ears ring continuously now. Skill saws did me in
building my two homes. In my day they didn't know about ear protection. When I
see young carpenters outside using skill saws without ear protection, I always
mentally wish them luck down the road."
Joe Ritacca wrote, "I used to be in the US Navy. I lost 25% of my hearing
due to machinery that I worked around. The point I would like to add is that at
higher noise levels (above110dB), it is advisable to have double hearing
protection. I used to wear ear plugs and ear muffs while working and I still
lost that amount of hearing. The machinery I worked around maintained a noise
level of about 120dB."
Fred Cohane also wrote about doubling up. "Similar to the concept of
wearing a belt AND suspenders, when I used to go to the firing range in a
former life, it was not unusual to wear ear plugs and ear muffs. My favorite
line is when guys stopped wearing hearing protection and would say, "Nah,
you get used to it,' or 'it doesn't bother me anymore.' They'll be in for a big
disappointment if the ever get their hearing tested."
Go to Tip #44 |
