Popular Woodworking 2004-04 № 140, страница 65

How Noisy is the Popular Woodworking Shop?

*Measurements were made with each tool used separately. The levels were higher with multiple tools in use.

pact human hearing than other scales that measure noise.

A 1998 NIOSH report said that 8 percent of workers without hearing protection who are exposed to noise levels of 85dBA during an eight-hour workday will experience some permanent hearing loss in their lifetime. For every 3dB increase, a worker should spend half as long exposed to the noise to prevent significant permanent hearing loss.

Industrial companies pay very strict attention to these workplace hearing safety recommendations. However, when it comes to leisure time noise concerns (such as woodworking), the only monitoring agency is you.

I've also heard woodworkers argue against hearing protection because they say they can't communicate easily while wearing it. If the noise levels in the workshop are below 80dBA, then yes, the ability to understand speech can be affected by hearing protection. However, when the noise pushes above 85dBA, it's been proven that hearing protection devices improve speech recognition (Noise & Hearing Conservation Manual; American Industrial Hygiene Association, 1986).

Why? As the noise gets louder, the lower frequencies (less than 1,000 hertz) in the noise will mask the higher speech frequencies (1,000-8,000 hertz). However, when a hearing protection device is used properly it will reduce the overall noise levels (mostly the lower frequencies) and the auditory system is able to regain use of the frequencies in the speech spectrum (500-8,000 hertz).

For those of you who think your hearing is already damaged and don't know why you should bother with protection, know this: Carelessly exposing yourself to even more damaging noise can only make your hearing loss worse.

So take a few simple steps to protect the hearing you still have.

How Loud is Your Shop?

The chart at right displays the noise levels of common power tools (running idle and while doing work) in the Popular Woodworking shop. While these tools may not be the same ones in your shop, the list should give you a good indication of the noise levels you're experiencing.

We've also included a chart on page 64 that illustrates the noises that are dangerous to your hearing. The colored column of the chart shows the amount of time you can safely be exposed to each noise level without causing hearing damage.

Once you use the charts to get an idea of how noisy your workshop really is, you're ready to learn all about the different types of hearing protection available, which are generally categorized as either muffs or plugs.

Noise-induced hearing loss is caused by exposure to high levels of noise in a work or recreational environment. Of the 28 million people in the United States with hearing loss, nearly one-third of them attribute their loss (at least partially) to noise exposure.

While it's not curable with medical treatment or surgery, it is preventable. Hearing loss can be temporary following exposure to noise, or it can be permanent following extreme, frequent or prolonged noise exposures.

While the degree or amount of hearing loss varies, there are some common signs:

• Increased difficulty communicating with family or friends.

• Increased difficulty communicating in social environments.

• People say you like the television or radio too loud.

Two Kinds of Muffs

All muffs are designed to completely surround the outer ear (technically called the "pinna"). Some specialized muffs are de-

• Increased difficulty talking on the telephone (either cellular or a land line telephone).

Another symptom of hearing loss is a noise heard internally that some people describe as ringing, buzzing or humming, called "tinnitus." More than 50 million Americans have tinnitus to some degree. Severe tinnitus can be annoying, distracting, distressful and can lead to loss of sleep.

Besides noise exposure, there are other causes of tinnitus, such as too much wax in the ear, head and jaw injuries, stress, cardiovascular disease, hypertension and medications (both over-the-counter and prescription). For people who experience tinnitus, suspect they have a hearing loss or have been exposed to loud noise, it is recommended they request a referral for a hearing test by an

signed specifically with visors, safety glasses and helmets.

Muffs vary in weight and comfort by the size of the headband, the earcup and the amount of

audiologist from their physician.

If you already know you have hearing loss, continuous or prolonged exposures to noise can further damage your hearing sensitivity. Take the steps to protect what hearing you have:

• Use hearing protection devices properly and regularly.

• Limit the time you are exposed to noise.

• Get your hearing checked by a professional. - CE

WHAT ARE THE EARLY SIGNS OF HEARING LOSS?

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