All parents complain at one time or another that their teenagers seem to hardly hear a word they say. An estimated fifteen in one thousand young people under the age of eighteen, however, do in fact have some degree of hearing loss. According to the National Institutes of Health, one-third of those cases can be blamed partly on our environment. Our ears are assaulted by excessive noise day in and day out: the teeth-grinding whir of a neighbor’s leaf blower; a temperamental car alarm shrieking in the distance; a jet airliner roaring overhead.
Sound volume is measured in units called decibels (dB). Sudden or extended exposure to lower sounds (85 dB or more) can potentially cause temporary or permanent hearing loss. This is called acoustic trauma. How loud is 85 decibels?
Surprisingly, not very loud, about equivalent to the bleating of city traffic as heard from inside your car. The Occupational Safety and Health Administration (OSHA), which regulates hearing safety in the workplace, mandates that employees should not be subjected to more than 90 dB over a period of eight hours, and never more than 115 dB.
Each 5-decibel increase in intensity reduces the safe-exposure time by half, so that the average rock-music performance (110 dB) begins to take its toll on kids’ hearing after just half an hour. Teenagers exposed to such high-intensity sound can and do experience transient hearing loss characterized by ear ringing. The effects of such brief duration acoustic trauma usually resolves in several days.
However, years of repeated exposure to hazardous levels of noise may lead to irreversible hearing damage, by destroying the tiny hair cells in the inner ear. With the loss of those cells, a person begins to experience difficulty hearing high-pitched sounds. In addition, the nerve fibers that transmit sound messages to the brain begin to degenerate, as do the corresponding nerves within the central nervous system. Eventually, the lower frequencies, where a good deal of speech is deciphered, become affected too. Although the symptoms of hearing loss may not emerge until later in life, the damage is already underway.
Symptoms that Suggest Hearing Loss May Include:
Loss of hearing sensitivity, first to high-pitched (high-frequency) sounds, then eventually to lower pitches
Difficulty hearing conversation, especially when other people are talking or there is significant background noise
Temporary or permanent ringing in the ears
A sense of fullness in the ears
Voices and other noises sound muffled and/or distorted
How Hearing Loss is Diagnosed
A thorough medical history and a physical examination, including an ear exam with an otoscope. Impedance testing, a hearing assessment for evaluating the functioning of the middle ear, and pure-tone audiometry, to test the softest level at which a young patient can hear various frequencies of sound.