One in 10 Americans has a hearing loss that affects his or her ability to understand normal speech. Age-related hearing loss is the most common cause of this condition and is more prevalent than hearing loss caused by excessive noise exposure. However, exposure to excessive noise can damage hearing, and it is important to understand the effects of this kind of noise, particularly because such exposure is avoidable.
Noise Exposure and Hearing Loss
Very loud sounds damage the inner ear by damaging the hair cells of the cochlea. When loud sounds are exposed to the ear for a short time, one may experience what’s called a temporary threshold shift, or a temporary hearing loss. This hearing loss may be accompanied by tinnitus (a ringing in the ears). One may recover from the temporary loss. But if the ear is exposed to loud sounds over longer periods of time, the hair cells can be permanently damaged, causing permanent sensorineural hearing loss.
Hearing loss usually develops over a period of several years. Because it is painless and gradual, it may go unnoticed. What you might notice is a ringing or other sound in your ear (tinnitus), which could be the result of long-term exposure to noise that has damaged hearing nerves. Symptoms of difficulty with word understanding, especially in a noisy environment such as a crowd or a party, are signs of hearing loss.
If you have any of these symptoms, they may be caused by impacted wax or an ear infection, which are relatively easy to correct. However, you may suffer from noise-related hearing loss. In any case, take no chances with noise—the hearing loss it causes is permanent. If you suspect hearing loss, consult an otolaryngologist or otologist. An audiologist can help document your current hearing level and can help manage hearing loss or help with obtaining the best hearing protection.
Dangerous Hearing Levels and Sound Measurements
People differ in their sensitivity to noise. As a general rule, noise may damage your hearing if somebody speaking at an arm’s length must shout to be understood. If noise is hurting your ears, your ears may ring, or you may have difficulty hearing for several hours after exposure to the noise. Noise is characterized by intensity, measured in decibels; pitch, measured in hertz or kilohertz; and duration.
Decibels (dB) measure the intensity of sound. The scale runs from the faintest sound the human ear can detect, which is labeled 0 dB, to more than 180 dB, the noise at a rocket pad during launch. Most experts agree that continual exposure to more than 85 decibels is dangerous.
Approximate examples of decibel levels:
- Faintest sound heard by human ear: – 0 dB
- Whisper, quiet library: – 30 dB
- Normal conversation, sewing machine, typewriter: – 60 dB
- Lawnmower, shop tools, truck traffic: – 90 dB
- Chainsaw, pneumatic drill, snowmobile: – 100 dB
- Sandblasting, loud rock concert, auto horn: – 115 dB
- The Occupational Safety and Health Administration’s limit for noise without hearing protectors: – 140 dB
- Gun muzzle blast, jet engine (such noise can cause pain, and even brief exposure injures unprotected ears): – 149 dB
Noise Exposure in Children
The National Institute on Deafness and Other Communication Disorders reports approximately 28 million Americans have lost some or all of their hearing, including 17 in 1,000 children under age 18. Noise exposure is increasingly common in the age of iPods and other personal music players. Overexposure to noise can cause both temporary and permanent hearing loss.
Portable Music / iPods: The maximum sound from an iPod Shuffle has been measured at 115 decibels, a level that can cause hearing loss to listeners of all ages. A survey sponsored by the Australian government found that about 25 percent of people using portable stereos had daily noise exposures high enough to cause hearing damage. Further research from the Netherlands reports that 90 percent of adolescents listened to music through earphones on MP3 players, almost half used high-volume settings, and only 7 percent used a noise limiter. Researchers at Boston Children’s Hospital determined that listening to a portable music player with headphones at 60 percent of their potential volume for one hour a day is relatively safe. The maximum volume limit can be set on many current MP3 players.
Wear hearing protectors, especially if you must work in an excessively noisy environment. You should also wear them when using power tools, yard equipment, firearms, or other motorized vehicles such as a motorcycle or snowmobile.
Hearing protectors come in two forms: earplugs and earmuffs.
Earplugs are small inserts that fit into the outer ear canal. They must be sealed snugly so the entire circumference of the ear canal is blocked. An improperly fitted, dirty, or worn-out plug may not seal properly and can result in irritation of the ear canal. Plugs are available in a variety of shapes and sizes to fit individual ear canals and can be custom-made. For people who have trouble keeping them in their ears, the plugs can be fitted to a headband. Specialty earplugs are available for activities such as hunting, playing music, and swimming.
Earmuffs fit over the entire outer ear to form an air seal so the entire circumference of the ear canal is blocked, and they are held in place by an adjustable band. Earmuffs will often not seal adequately around eyeglasses or long hair, and the adjustable headband tension must be sufficient to hold earmuffs firmly in place.
Earplugs and earmuffs can be found at most pharmacies and home improvement stores.
Hearing with Earplugs In Place
Just as sunglasses help vision in very bright light, so hearing protectors enhance speech understanding in very noisy places. Even in a quiet setting, a normal-hearing person wearing hearing protectors should be able to understand a regular conversation.
Hearing protectors do slightly reduce the ability of those with damaged hearing or poor comprehension of language to understand normal conversation. However, it is essential that persons with impaired hearing wear earplugs or muffs to prevent further inner ear damage in very noisy places.
It has been argued that hearing protectors might reduce a worker’s ability to hear the noises that signify an improperly functioning machine. However, most workers readily adjust to the quieter sounds and can still detect such problems. If a worker is already hearing impaired, he or she needs expert advice about how to protect against further damage. In some cases hearing aids can be used under earmuffs.
Earplugs at Concerts
Parents should be aware that various medical studies have found sound levels at rock concerts often to be significantly higher than 85 dBA, with some reports suggesting that sound intensity may reach 90 dBA to as high as 122 dBA. Frequent concertgoers may experience some potentially irreversible hearing loss from their experience.
A research study, “Incidence of spontaneous hearing threshold shifts during modern concert performances” (Opperman, Reifman, Schlauch, Levine; Otol-HNS 2006, 134:4: 667-673), examined sound intensity throughout a well known concert venue, and the effectiveness of earplugs. The findings stated that sound pressure levels appeared equally hazardous in all parts of the concert hall, regardless of the type of music played. Accordingly, you should use earplugs at every type of musical concert, regardless of your distance to the stage.
A good rule of thumb: When a child accompanies a parent to any activity or location with excessive noise, ear protection should be worn by the entire family.