PROTECT YOUR HEARING

Noise is a common byproduct of modern civilization. Most of us have learned to live with it. What do we mean when we use the word sound or noise? Well, sound is anything a person hears. Noise is any sound a person hears and does not like. Over the course of time, practically every new machine invented added a new noise for us to contend with. And with each advance of modern science, the problem of noise is getting worse, not better. And if it's hard enough to live with everyday noise, it's even harder to work with. This man uses a welder's helmet to protect his eyes and face. But, what about his ears? Are they less important? The only thing his ears know about noise is that it feels so good when it stops. With modern electronics, sound can be seen as well as heard. Every sound has its characteristic frequency related to pitch. Another characteristic is intensity or loudness. The frequency of a sound is measured in the number of vibrations or cycles per second. Although the frequency range for the young human ear extends from 20 to 20,000 cycles per second, most people cannot hear sounds above 10,000 cycles per second. The frequencies most important for understanding speech are from 500 to 2,000 cycles per second. Sounds at frequencies above 20,000 cycles per second are designated ultrasonic and are beyond the range of human hearing. Frequencies below 20 cycles per second are called subsonic and are seldom heard except as vibrations which are felt as intensity increases. The ear is an amazingly versatile hearing instrument. It can react to the rustle of the wind in a leaf in the silence of the night. It can easily detect the faint hum of a mosquito. And millions of times louder, the sound of the swat is also easily accommodated. The loudness or intensity of a given sound is measured by the pressure level in units called decibels or dB. For example, a whisper is about 20 dB. Low street noise, about 40. Conversation, 60 dB. Heavy traffic, 80. An average factory, 100 dB. A boiler works, 120. A jet engine, 140. 0 dB is a reference level only and is generally accepted as the approximate level where the faintest sound can be heard by a person with normal hearing in a quiet environment. The loudness of a sound increases as the sound pressure level increases. In order to protect this delicate instrument, it's important to know the ear and how sound affects it. Sound waves are conveyed by the external ear to a tube-like passage sealed by the eardrum which they set in motion. From here, the vibrations are carried across a tiny bridge of small bones to the inner ear. The sound is amplified about 22 times as it makes this passage to the real seat of hearing, the inner ear. Inside the inner ear are thousands of microscopic hairs, shown here in very simplified form, responding to the sound energy transmitted to them. They stimulate a nerve leading to the brain and you hear. Different hair cells react to different sound frequencies. Sound can also reach the inner ear through the skull, particularly through the mastoid bone. While this sound is greatly reduced or attenuated, the mastoid area is the most sensitive to sound outside the ear itself and must be considered when protecting against hearing loss. Too much noise all at once can result in sudden loss of your hearing. Then there is the more gradual hearing loss, much more serious because it affects more individuals. Gradual loss comes from short duration exposure to high intensity sounds in the range of 100 to 130 dB. In the lower range of danger, from 85 dB up, long exposure to noise can also cause loss of hearing. The effect is the same whether it happens in a short or long period of time. The hair cells in the inner ear can be disabled temporarily or permanently by too much exposure to noise. They become fatigued and fail to send the proper signals to the brain. It's hard to notice this. The first to tire are those sensitive to the higher frequencies above the normal speech range. Sometimes fatigue causes ringing ears. Seldom is there any pain. If there is, the loss is serious. If you can give your ears a rest from noise, they may recover, at least partially. Otherwise, the loss is permanent, even though gradual. There may come a time when you will miss sounds coming from the next room. Maybe you really don't hear the telephone. When this happens, watch out. Then, one day, you'll realize you're not even keeping track of individual voices in a group. This can be embarrassing, even hurt your career. In setting up a noise abatement program, the first step is to measure the noise levels and plot them for easy analysis. Look for trouble areas and try to do something about them. Where feasible, areas of extreme noise should be isolated or shielded through engineering methods. Periodic tests should be made when new equipment is brought in. All employees exposed to high levels of noise should have hearing checks made before employment and at regular and frequent intervals thereafter. There are several forms of hearing protection. Regardless of the type, the effectiveness of the device depends largely on the fit. It's been proven that cotton, formerly used extensively, gives very little protection against noise. Ear plugs are a popular form of hearing protection. Knowing how to use them properly, plus their limitations, is most important. There's more to it than just jabbing the plug into your ear. They should be fitted by a doctor or other medically trained person. Every ear is different. Some people require different sizes or types for each ear. Unless the fit is absolutely correct and tight, ear protection from plugs is materially reduced. Another point to remember is that jaw movement loosens plugs. Unless they are reseated periodically, the plugs may do nothing to protect the ear. The muff type ear protector has several outstanding advantages. It gives positive, comfortable ear protection without special fitting. The exposed ear, which acts as a funnel for sounds coming from all directions, is covered and sealed by the muff type ear protector. This acts like a helmet or shield to deflect most of the sound hitting its outer surface. The amount of noise reaching the ear after having been deflected or filtered is greatly reduced or attenuated. Conversations can be heard better in a noise area when wearing earmuffs because the greater portion of the background noise disturbing to the speech sounds has been eliminated. When work involves exposure to noise, do not stop at halfway protection. Select an ear protector that shields your ears both inside and out as does the muff type ear protector. This compact, lightweight ear protector is easy to adjust as most muffs are and gives excellent protection against loss of hearing when exposed to noise. If you're a mechanic tuning up a jet engine, for example, you have to communicate with the people in the cockpit as well as work in a noise field of 145 dB. Under extreme noise conditions like this, both ears and microphone are protected with muffs. For less noisy conditions inside the cockpit, this combination headset and microphone permits clear communication yet attenuates noise to a safe level for prolonged periods of exposure. Today, men in a wide range of noise occupations will find an ear protector available for most exposures. This combination of a safety cap and a modern muff type ear protector allows this man to work comfortably under extreme noise conditions with complete protection. These men can work in safety and comfort in dangerous noise areas. Only noise which has been reduced to safe levels ever reaches the organ of hearing. So, if you're one of the thousands who must live with noise and work steadily under conditions that might lead to serious injury to your ears, make sure you have adequate reliable ear protection whenever you are in a high noise area. Remember, it's not enough to be provided with good ear protection. The only effective ear protector is the one you wear. You owe it to yourself and to your family to protect your hearing. Remember, your hearing is one of the most precious gifts you have.