American Medical Association Family Medical Guide - American Medical Association [713]
Prolonged exposure to noise (especially high-pitched noise) at or above 90 decibels can damage the sensitive hair cells lining the cochlea (the part of the ear that transmits sound information to the brain) and cause partial to severe hearing loss. Being constantly exposed to loud machinery (such as jackhammers or tractors) or listening to extremely loud music (whether on headphones or at a rock concert) can harm your hearing. A one-time or brief exposure to a loud noise (such as a gunshot or from fireworks) can cause temporary hearing loss.
Decibels Type of Sound Effect on Hearing
10 Barely audible Safe
20 Ticking watch Safe
30 Soft whisper at 16 feet Safe
40 Suburban street (no traffic) Safe
50 Interior of typical urban home Safe
60 Normal conversation Safe
70 Noisy restaurant Safe
80 Loud music (including personal stereo) Safe
90 Truck at 16 feet Risk of injury
100 Typical rock concert Risk of injury
110 Jet engine at 800 feet Risk of injury
120 Jackhammer Injury
130 Jet engine at 100 feet Injury
The table below lists the decibel levels of some sounds and their effects on hearing.
How to Protect Your Hearing
Take the following precautions to prevent permanent damage to your hearing due to noise:
• Wear earplugs made of foam, plastic, wax, or rubber to mask noise.
• If you are exposed to a loud sound, eliminate the sound or cover your ears and get away from the source of the noise as quickly as possible.
• Keep the volume of music in your car and home at a comfortable level. If you wear headphones, set the volume at a level that is inaudible to others. If other people can hear the music coming from your headphones, it can damage your hearing.
• If you work in very noisy conditions, wear ear protectors that are designed to decrease sound volume by 40 to 50 decibels. If you need to communicate with coworkers while wearing ear protectors, a small microphone and earphones can be added to the ear protectors. Have your hearing tested frequently if your employer doesn’t regularly test your hearing. If you think that the noise level where you work is too high, contact the person responsible for safety at your workplace, or your local health department or the office of the Occupational Safety and Health Administration (OSHA).
• If you hear ringing or other noises in your ear (tinnitus; see page 1020) after exposure to a loud noise, the noise was too loud. Take precautions to avoid exposure to the noise in the future.
Diagnosis
If you have hearing loss, your doctor will take a detailed health history and examine your ears. He or she will refer you to an otologist (a doctor who specializes in disorders of the ear), who will examine your ears and perform simple hearing tests. You also may have specialized hearing tests (see next page) to confirm the diagnosis.
Treatment
If the hearing loss caused by otosclerosis is mild or occurs in just one ear, treatment may not be necessary, or you may only need a hearing aid (see page 1018).
If the hearing loss is severe, your doctor may recommend a procedure called stapedectomy. In stapedectomy, the stirrup is removed and replaced with an artificial bone made of plastic or metal to allow sound waves to reach the inner ear. If both ears are affected, one ear will be operated on first and given time to heal before the second one is operated on. Hearing after a stapedectomy usually does not improve immediately because a blood clot forms in the middle ear, and the eardrum swells. As the clot gradually disappears, hearing improves (usually about 2 to 4 weeks after the procedure).
People who have only a conductive hearing loss benefit more from stapedectomy than do people who have both conductive and sensorineural hearing loss.
Hearing Loss
Hearing loss is a worsening of hearing that can include muffled hearing or difficulty understanding or differentiating sounds or words. Hearing