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Noise-Induced Hearing Loss and Its Prevention

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What is the importance of noise-induced hearing loss?

The industrial and technological revolution may have propelled society to higher levels of achievement, but this progress has also made the world a noisier place in which to live. In fact, noise pollution is a growing health hazard and can be found almost everywhere. Car alarms, leaf blowers, gunshots, boom boxes, and traffic congestion fill our cities with decibels (the measure of sound intensity). Escaping to the country may not provide a quiet refuge, and even farmers are at high risk for exposure to noise from their farm machinery.

What's more, potentially harmful noise is not necessarily unpleasant or unwanted. For example, the music at a concert and the pounding of a jackhammer on the street can be equally damaging to the inner ear. The reason for this is that any sounds (acoustic energies) delivered with equal intensity, regardless of their source, are equally dangerous. Eventually, continued or repeated exposures to high intensity sound can cause acoustic trauma to the ear. This trauma can result in hearing loss, ringing in the ears (tinnitus), and occasional dizziness (vertigo), as well as non-auditory effects, such as increases in heart rate and blood pressure.

One-third of the 30 million Americans with hearing loss have an impairment that is at least partially attributed to excessive noise exposure. Noise remains the most common preventable cause of irreversible sensorineural (involving the ear's sensory nerve) hearing loss.

What are acoustic trauma and noise-induced hearing loss?

Acoustic trauma occurs when any excessive sound energy strikes the inner ear. If it is brief, the noise may cause a reversible, temporary hearing loss, technically known as a temporary threshold shift. For example, after a loud rock concert, it is common to experience hearing dullness and ringing in the ears for several hours. In this situation, if symptoms persist beyond several days, oral steroids (cortisone-type medications) may help the inner ear to recover. If the noise is loud enough and the duration of exposure long enough, however, it may cause a permanent threshold shift. This condition is called noise-induced hearing loss, which has no cure and is irreversible.

Sudden hearing loss produced by a sudden and very loud noise (blast injury) is called acute acoustic trauma. If the sound is loud enough, it can cause the eardrum to rupture or the person to have a complete loss of hearing. Sometimes, particularly if the sudden loss is total and occurs combined with dizziness, immediate surgical exploration of the ear may be necessary. In this circumstance, the ear surgeon may need to locate and patch a hole (perilymphatic fistula) between the inner ear fluid space and the middle ear space.

Picture of the Inner Ear Structure

Picture of the Inner Ear Structure



Source: MedicineNet.com
http://www.medicinenet.com/noise_induced_hearing_loss_and_its_prevention/article.htm

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