Woodworkers Club of Houston

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Protecting Your Employees from Unwanted Noise 


by Eric A. Patton
Training Manager
Dalloz Safety
Reading, Pa.

Noise is all around us

Noise can be in the factory, the construction site, the nightclub, the office and in the home.

We are surrounded by noise

Industrial and construction machinery, motors, generators, lawn care equipment, vacuum cleaners, race cars, stereos and even some childrenís toys can all be a source of potentially hazardous noise. We try, but canít escape it.

Itís important for us to realize that we encounter noise everywhere, not just at work. Noise infiltrates our private lives. It invades our space. It bothers us, aggravates us and keeps us up at night. Noise raises our blood pressure, gives us a headache and makes us irritable around our fellow workers as well as our friends and neighbors.

Noise can also rob us of one of our most precious and cherished senses ó our ability to hear. Imagine not being able to understand daily conversations with our family, friends and coworkers. Imagine not being able to enjoy the sound of our children singing in the school choir concert or playing in the marching band. Imagine becoming isolated from the world around us. Youíll begin to understand and appreciate why protecting your hearing is so important.

Noise can be described as unwanted sound. Not all sound is unwanted. There are many important sounds that occur at work or at home that we want and need to hear. We need to hear verbal communication from our coworkers. We need to hear the sound of the machine weíre using. We certainly need to hear warning sounds such as alarms and verbal alerts. We want to hear these things and, at the same time, protect our hearing from hazardous, unwanted noise.

Dealing with noise

Identifying and addressing a noise exposure hazard can be, at best, a challenging project. Noise exposure can be described by two distinct characteristics: Sound pressure level and frequency. To put it into understandable terms, sound pressure level can be roughly compared to loudness or intensity.

A very simple and nonscientific method to help determine if a noisy environment is approaching a potentially hazardous sound pressure level is commonly referred to as the "armís length rule" or the "3-foot rule." While standing in the noisy area, attempt to carry on a normal conversation with another individual who is standing an armís length away or approximately 3 feet away from you. If you find you need to raise the level of your voice in order for the other person to understand everything you are saying, or vice-versa, the background noise may be approaching a potentially hazardous level. If this is the case, further investigation is warranted.

A more scientific approach incorporates the use of one or more commercially available instruments for measuring sound pressure. Portable, hand-held sound level meters can be quite inexpensive and will measure ambient sound in a given area, displaying sound pressure level in decibels (dB). Handheld octave-band analyzers are more expensive, but permit more in-depth investigation into not only the sound pressure level, but also the frequencies where the sound is most powerful. Octave band analysis is not only the preferred method of measuring a noise exposure problem, but is extremely important in choosing the most effective hearing protectors and engineering control measures. Dosimeters, which are typically worn by an individual throughout the day, will provide additional insight in regards to individual noise exposures.