Can You Hear a Pin Drop? - Loud noise can destroy hearing

  • Published
  • By Dr. Daryl Hammond, Chief Electrical Engineer
  • Air Force Civil Engineer Support Agency
Tyndall AFB, Fla. --  Airplanes, cars, trains, lawn mowers, and even radios and television create unwanted sound, which we call noise. When soft and mild, noise is tolerable; but when it becomes too loud, it can be annoying and even destroy hearing.
     Once hearing loss from noise occurs, it will never return to normal. The changes are subtle, and you might not even know there's a problem.

You may be unconsciously turning up the TV or radio volume, or blaming other's poor speech for your difficulty in distinguishing between certain consonant pairs that fall in the region where noise-induced hearing loss occurs (for example, D and B, or F and S).

I was one of those people. Years of working around loud engines, generators, and aircraft without proper hearing protection permanently damaged my hearing.

Every day, I see people -- flight crews, aircraft maintenance personnel or civil engineering grounds maintenance personnel -- making the same mistake I did: not wearing hearing protection or wearing it improperly. Before it's too late, protect your hearing and preserve your quality of life so you can continue to enjoy the sounds of nature and music and understand all of the conversation around you.

Hearing Basics
How does noise cause hearing loss? Reviewing the basics of how we hear, our auditory system is divided into the outer, middle and inner ear. Sounds are gathered by the outer ear and funneled down the ear canal to the eardrum. At the eardrum, sound is changed into vibrations. These vibrations are picked up by three tiny, connected bones located in the middle ear. These bones couple the sound to the inner ear where it is changed into electrical impulses by tiny hair cells connected to the auditory nerve. The brain interprets the impulses and decides what the sound is and where it's coming from.

When loud noises occur, the tiny hair cells located in the inner ear become disfigured, flattened or fused together. This damage is irreversible and causes permanent hearing loss. Only by using protective equipment or by getting away from the noise can additional damage be prevented. ... So how loud is too loud?

We know whispering and tiptoeing are soft sounds while lawn mowers, guns and screaming are loud sounds. Sounds are measured in what we call decibels, but understanding the scientific jargon about how sound is measured or how it affects us can be confusing.

Air Force Occupational Safety and Health Standard 48-20, Hearing Protection Conservation Program, explains the terms, but sometimes it's just easier to remember the following general rule-of-thumb when it comes to noise: It's too loud when it hurts your ears or you have to raise your voice to talk to someone.

Line of Defense
You've got to protect your hearing by either getting away from the noise or by wearing hearing protection, such as earplugs, earmuffs or both. But these devices help prevent noise induced hearing loss only if they are worn consistently and correctly.

Earplugs are the most popular type of hearing protection. They come in many forms, but those made of yellow expandable foam that conforms to the ear canal are most familiar to us. To be effective, they must be installed properly, which means inserting them well into the ear canal to seal it entirely. Earmuffs fit over the ear to form an air seal and will not seal properly around long hair or eyeglasses.

Whether earplugs or earmuffs are chosen, proper fitting is essential to obtain the best results.

Importance for Air Force Workers
Noisy environments are a common occurrence for many Air Force specialists, such as aircraft mechanics, aircrew members, airfield and weapons range operations experts, and civil engineering workers. All of these people are exposed to dangerous levels of noise every day from vehicles, aircraft or other machinery. Air Force Occupational Safety and Health guidance requires all workers to wear hearing protection devices when performing duties in a noisy environment and to be trained on their proper wear.

Additional information about assessing workplace noise levels, safeguarding your hearing and proper wear of hearing protective devices can be obtained from your base bioenvironmental engineering or occupational health and safety office. Audiologists in the Aural Displays and Human Effectiveness Directorate of the Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio, also can answer your questions.

Remember -- maximum protection of hearing can only be accomplished if hearing protectors are used and properly worn. Please take the time to correctly use earmuffs and install earplugs. It may mean the difference between hearing, or not hearing, a pin drop.