Reprinted from the ACJ - September, 2000
Pneumatic Wrenches screaming, compressor squealing, country music warbling. "Break time! Let's go outside." "Who Died?" "No, I said Break Time!" "Yeah, yeah, I'll fix that brake line, right after we get some coffee." "You too? I just got over a cold. Lot's of sniffling and coughing! You want to get some breakfast?" " Huh? Oh, I see her. Your right, that's some great..." Sound familiar?
Shops are noisy. It's a fact of life in the automotive repair business. We can't get rid of the tools and hoists and torches. So how can we protect ourselves from the din without breaking the bank? "Dean broke his back? That's terrible." There are several ways to reduce the noise in your shop or plant without too much work or money. Start by taking an `Ear' tour of your facility. Listen for the loudest sources of noise. High pitch noise especially, as this type damages our hearing the most.
Noise can get at us in two ways; direct and indirect. A guy grinding a part is directly affected by the sound waves emanating from the grinder. In addition, the guys across the shop are indirectly effected by the sound waves bouncing off the floor, ceiling and walls. The surfaces in most shops are concrete, brick and steel. All of which reflect sound well. Like a ping pong ball in a box, it careens about until we capture it with our eardrums.
A note about noise. As a weed is just a flower you don't like; noise is just a sound we don't care for. It has two components; quantity (loudness) measured in Decibels, and quality (tone) measured as Frequency. Loudness can range from a whisper of 10 decibels to an airplane taking off at 120 decibels. Here is the twist. "You hurt your wrist?" The scale used to measure decibels is logarithmic. This means the difference between a noise at 60 decibels is not 20 % louder than a noise of 50 decibels. It has 10 times the sound energy. That's a lot of force hitting your ear drum. On the flip side, reduce the noise of a machine in your shop by 10 decibels and you reduce the sound energy bombarding your ears by 10 times. "No sorry. I got a couple of quarters, but I'm out of dimes." The frequency of sound relates to it's pitch. High frequency - high pitch. The higher pitched noise, like that from air guns or grinders, damages our ears the most. But the lower frequencies can still do damage and are distracting in a big room. So what do we do. Simply put, block the noise. At the source or at the reflection. Enclosing a loud machine, such as a compressor, in a plywood box lined with foam will capture most of the noise and help keep you from needing to spend time in your own padded room. Mufflers on air tools also help a lot. "Yeah I guess Hell is hot. Why do you ask?" Flexible sound curtains are available. Hang them around equipment or hang them strategically to keep noise, and you, from bouncing off the walls. Like your old van from the seventies, you could cover all the walls with carpeting, but vacuuming the ceiling of the shop is a real drag. Earplugs, earmuffs and earwax all work to reduce noise impact on the receiving end, your head. Some fancy earmuffs are equipped with `antinoise' sound deadening systems. They send out a frequency of sound inverse to the noise that cancels it. I won't explain it, mostly because I can't. But it works. No fair using them to block the voice frequencies of complaining customers, nagging spouses, or whining kids.
Reducing the noise level in your facility via these simple methods will have a soothing effect on everyone's nerves and can increase safety in the shop by allowing a cry of warning to be heard clearly. "Hey watch out! That hood's prop rod is slipping!" "The hot rod is sleeping? This is an escort, what are you talking abow, ow ow ow!" "Bow Wow Wow. I used to listen to them in my van. You know it had good carpet on all the walls. You OK?" "Yeah I think so. You're right, hood got my head, prop rod in the..."
The above article was written by David M. Brown, Chief Engineer of Johnson Manufacturing Company, Inc. and is published by JOHNSON with the expressed approval of the National Automotive Radiator Service Association and the Automotive Cooling Journal. Other reproduction or distribution of this information is forbidden without the written consent of JOHNSON and NARSA/ACJ. All rights reserved.
JOHNSON MANUFACTURING COMPANY
114 Lost Grove Road / PO Box 96 / Princeton, Iowa 52768-0096
Phone 563-289-5123 or Fax 563-289-3825