Hearing Conservation Calvin College
The Effects of Noise on Hearing • Continuous exposure to excessive levels of noise may cause irreversible hearing loss. Such loss is exhibited by a shift in the ear’s ability to perceive audible sound. • Initially, brief noise exposure may cause a temporary decrease in hearing sensitivity, that typically returns to its former level within a few minutes to a few hours. • Repeated exposures lead to a permanent threshold shift, an irreversible hearing loss.
What’s the purpose of hearing protection? • When properly used, hearing protectors can lower your noise exposure below 85 decibels where it will not cause hearing loss.
Types of Hearing Protection • Each type of hearing protection offers a potential reduction of noise called the Noise Reduction Rating (NRR). The NRR for each type of hearing protection will be printed on the package. • They types of hearing protection available at Calvin are: • Ear Plugs • Formable Plugs • Premolded Plugs • Ear Muffs
Advantages: Inexpensive Convenient May be worn with other PPE Universal Fit Disadvantages: Poor Sanitation Easily worn incorrectly Difficult to use when cold May contribute to ear infection Advantages and Disadvantages EAR PLUGS
Advantages: Convenient Complete ear protection Reusable Disadvantages: Hot Fit is affected by other PPE Less comfortable Size Advantages and DisadvantagesEAR MUFFS
Selection • Hearing protectors can be very effective but only if they fit properly and are worn correctly. • The more carefully you select and wear hearing protectors, the higher your protection will be. • Hearing protectors may feel uncomfortable at first, but give yourself a chance to get used to them, just as you do with a new pair of shoes or glasses.
Earplugs Formable Plugs • Fit: One size fits most. Foam plugs gently expand to provide a snug and secure custom fit. • Use: Slowly roll and compress foam plugs into a very thin cylinder. While compressed, insert plug well into the ear canal. • Maintenance: Keep plugs clean and free from material that can irritate the ear canal. Discard plugs if they harden or do not re-expand to their original size and shape.
Earplugs Premolded Plugs • Fit: Premolded plugs are made from flexible materials which are preformed to fit the ear. Most premolded plugs are sold in two or more sizes and must be individually sized for each ear. • Use: Reach around the back of you head and pull outward and upward on the ear while inserting the plug until you feel it sealing. • Maintenance: Premolded plugs will normally last several months. They should be replaced if they shrink, harden, tear, crack, or become permanently deformed. Wash them in warm soapy water and rinse well. When dry store in a carrying case.
Earmuffs • Fit: Earmuffs have rigid cups with soft plastic cushions which seal around the ears to block noise. • Use: Muffs must fully enclose the ears to seal against the head. Adjust the headband so cushions exert even pressure around the ears to get the best noise reduction. No hair should be beneath the cushion. • Maintenance: Cushions can be cleaned with warm soapy water and rinsed thoroughly. Do not use alcohol or solvents. Cushions need replacing whenever they become stiff, cracked or do not seal. Don’t modify earmuffs in any way, and especially do not stretch or abuse the headbands as this will reduce your protection.
Rules of thumb • When either a plug or muff is properly fitted, the sound of your own voice should change, becoming deeper, hollow or muffled. If you don’t hear the change, or if it isn’t the same in both ears, you haven’t obtained a proper fit and acoustic seal in either one or both ears. • When you feel the need to shout in order to be heard three feet away, the noise levels are probably 85 dBA or more and hearing protectors are recommended.
Audiometric Testing Audiometric testing measures your ear’s ability to pick up different frequency sounds. This is the best way to check if any of your hearing cells are no longer picking up sound. Hearing loss is a slow, gradual process and this test can pick up changes that you may not have noticed.
Audiometric Testing Cont. • If you having measurable hearing loss, this is called Standard Threshold Shift (STS). • This measurable loss can be caused by a number of things such as a head cold, listening to loud music, working without your earplugs, etc. • Audiometric testing is required for all Calvin employees whose job may expose them to noise levels at or above 85 decibels.
Audiometric Testing Cont. • A second test is performed within 3 weeks if any STS is picked up during your initial test. • It is generally best to do the testing before you begin your work.
What is Audiometric Testing? • You will be asked not to expose yourself to loud noise for 14 hours prior to test. If you are to tested after you been at work you must wear hearing protection prior to the test. • You will be seated in a sound proof booth and will be given headphones. • The audiometric technician will ask you to signal when you hear different tones. • Tests will be separate for each ear and for different frequency ranges. • The test takes about 10 minutes.
What is Audiometric Testing? (Cont.) • The results of the test show how you were able to detect the different frequency sounds in the test. • Your annual audiogram will be compared to your previous test results and maintained in your employee file.