Can you hear me now? Good! - Crossfeed

Mech, Fall, 2003 by Don Borkoski

Too often, Sailors visit medical and find out in an audiogram their heating has degraded. Did you know that hearing loss is cumulative and once lost never can be regained? Who is supposed to protect your hearing? The right answer is you!

Your ears are sensitive devices. The outer ear collects sound and channels it to your ear drum. The drum vibrates with the sound and rattles three small bones: the hammer, anvil and stirrup. These items change sound waves into mechanical vibrations in the middle ear. Your inner ear is the most sensitive part of your hearing device. The small bones of the middle ear squish the fluid around inside semicircular canals. The fluid then flows through the cochlea where little hairs called cilia wave around with the fluid motion.

The cilia are full of very sensitive nerves that change that fluid motion into nerve impulses that travel through your auditory nerve to your brain, and your brain then senses Emme & Emme with an amplified subwoofer thump.

So what's the problem you ask (Good to hear you're using ORM step 1 : identify hazards). The problem is that cilia are very sensitive, and, like seaweed in a storm, they permanently can be bent or broken. When they break or bend, the more hearing you lose. Unfortunately, they don't grow back, and you suffer permanent loss.

Two basic types of noise exist: continuous (sound over a prolonged period of time) and impulse (sound that starts and stops abruptly). Depending on the loudness and duration, both can be harmful.

Loudness is measured in decibels, which is recorded as db. Your cilia can handle impulse noise up to 85db and continuous noise at 85db for 8 hours without heating loss. Any sound or noise louder or for longer durations break or bend the cilia causing permanent hearing loss.

Did you know that almost daily everyone losses part of their hearing? Most lawn mowers, vacuum cleaners, and stereos generate noise from 85 to 95db. Chain saws, power tools, car horns and Harley-Davidson motorcycles with straight pipes, range from 110 to 120db. Worst of all, gunshots, jet aircraft, and amplified stereos with high-power subwoofers make noise that exceeds 140db!

Although hearing loss usually is permanent, it is preventable. At home and work, hearing-protection devices and reasonable volume levels on the stereo can dampen continuous and impulse noise to levels that will not damage your cilia.

Hundreds of hearing-protection devices exist and will help. Disposable devices are convenient, but reusable ones work best when you constantly take them in and out. Ear muffs are more comfortable, permanent and best used for double protection. NAVOSH requires double protection for any exposure over 140db.

The best heating-protection device is the one you'll use. Most devices attenuate noise about 20 to 30db. When two devices are used, the noise is attenuated almost 60db. So it makes sense to keep different devices on hand. A good goal is to use protection to lower the noise level below 85db. An industrial-hygiene survey will tell you the noise levels in different areas. Look for posted signs. Or better yet, just listen. If the noise sounds loud or hurts, you need protection! Keep your cilia up, abstinence is best, but, at least, use protection, and turn that damn stereo down.

CW04 Don Borkoski is the avionics, electrical and ALSS branch head at the Naval Safety Center.