Remember the days when your parents told you to turn down the music on your stereo, and history repeated itself when you raised your own children? Or how about those Fourth of July parades featuring massive fire engines blaring their sirens in close proximity to where you and your grandchildren were standing? Everybody’s ears were still ringing by the time you all went to see the local fireworks celebration that same evening.
Today, you can still find teenagers in any town blaring music their parents hate, although earbuds seem to be permanently attached to their heads these days. Therefore, it’s more likely their parents don’t know what they’re playing. Blasting music through earbuds actually poses a bigger risk to hearing than the records you played on stereos and boom boxes. You could also visit towns across the country where fire engines still blare their sirens in parades to the delight of squealing children and later in the evening, host noisy Fourth of July firework displays.
These are just a few of the leisure activities associated with loud noise exposure. The risk of losing your hearing from occupational-related noise is greater, especially in certain industries.
Often, a person doesn’t realize they’ve incurred hearing damage from noise exposure until it’s too late. These early warning signs can turn into permanent hearing deficits:
Temporary hearing loss can last up to 48 hours after a loud noise exposure
The most recent data from the Centers for Disease Control and Prevention (CDC) indicates an estimated 24% of adults in the U.S., ages 20–69 have signs of permanent damage to their hearing from excessive noise exposure. NIHL is a global problem, and the second most frequent type of sensorineural hearing loss after age-related causes. Noise exposure is a common occupational risk factor that leads to several detrimental health effects, including hearing loss, tinnitus, irritability, insomnia, and fatigue. Noise is generally viewed as an unpleasant sound associated primarily with transportation and heavy industry occupations. Yet noises associated with leisure and everyday activities can also lead to hearing loss, including:
Noise exposure damages the sensory cells of the inner ear (cochlea) and the outer hair cells. Two primary theories exist on the precise mechanisms that cause this damage. The first is that constant noise exposure may be secondary to multiple instances of microtrauma; similar to the acoustic trauma injury produced by impulse noise. Although an industrial-related explosion is the most common type of impulse noise resulting in acoustic trauma, remember the fire engine’s blaring sirens and loud fireworks? These are two other examples of impulse noise that can cause acoustic trauma. The second theory is that sustained noise exposure over long periods of time leads to auditory fatigue and metabolic exhaustion, resulting in cell death.
NIHL is a complex disease that results from occupational or recreational noise exposure, coupled with other risk factors. These include environmental exposure (fireworks, loud music, gunfire, sirens), ototoxic medications (drugs that cause hearing-related side effects), and genetic risk factors. The latter is believed to play a role in NIHL susceptibility, because multiple studies have shown individuals exposed to the same or similar occupational noise exposure don’t suffer the same hearing loss.
A 2019 study identified 14 genetic variations called single nucleotide polymorphisms in 10 different genes linked to a risk of NIHL. These findings suggest that genetic susceptibility plays an important role in NIHL incidence, and that this information should be used as one method of identifying individuals at higher genetic risk.
Think of decibels (db) in the same way as inches, except they’re a unit of sound measure rather than a unit of distance. If you learned about inches as a young child, it’s easy to relate to this measurement in everyday situations. But unless you work in an audio-related industry, you’re probably not thinking in dB.
The degree of NIHL depends on the dB level, distance, and duration of exposure. In 1999, the World Health Organization (WHO) Guidelines for Community Noise concluded that a 24-hour equivalent sound level of less than 70 dB would prevent hearing impairment in 95% of the population, despite lifetime exposure. Long or repeated exposure to sounds at or above 85 dB can cause hearing loss. And the louder the sound, the shorter the duration it takes to incur damage to your hearing. To put this in perspective, here are some comparative dB ratings:
At the maximum volume level of 105–110 dB, personal listening devices, extremely loud radios, stereos, or televisions, and loud entertainment venues (e.g. nightclubs, bars, and rock concerts) can cause hearing los s in less than five minutes.
Studies analyzing noise at different sporting events found exceedingly high dB ratings, putting attendees at greater risk of developing NIHL:
Wearing personal hearing protection devices (e.g. ear muff or ear plugs) at sporting events can prevent NIHL. Unfortunately, a 2018 survey of 6,357 U.S. adults ages 18 and older found that 81.8% never or seldom wore this type of device at loud athletic or entertainment events. A prior study concluded that a large number of people at risk of NIHL with an understanding of the side effects of noise exposure chose to refrain from using hearing protection.
Every year, about 22 million U.S. workers are exposed to noise loud enough to damage their hearing. As such, NIHL is one of the most common work-related illnesses in the U.S. NIHL can lead to reduced efficiency in the workplace and permanent dysfunction in other aspects of life. Noise is a common occupational hazard for people who work in the iron and steel industry, foundries, mining, saw mills, textile mills, airports and aircraft maintenance shops, crushing mills, traffic-related and transportation jobs (e.g. tool booth operator and subway conductor), etc.
The National Institute for Occupational Safety and Health (NIOSH) recommends that workers should not be exposed to noises that exceed 85 dB for 8 hours. The Hierarchy of Control is a three-prong principle that occupational safety and health professionals use to reduce or eliminate dangerous noise. If the noise cannot be completely eliminated, engineering or administrative changes should be made to the workplace to minimize noise exposure. When the first two options have been exhausted, hearing protection devices should be made available to all workers exposed to noise, at no cost. NIOSH’s Buy Quiet initiative encourages companies to purchase quieter machinery and tools to reduce worker exposure to loud noise.
WHO has set a limit of 100 dB for ceremonies, festivals, and entertainment events, with a recommendation to never exceed 110 dB and restrict exposure to less than five concerts a year. In relative terms, a chamber music concert in a small auditorium is 75–85 dB. When the rock group KISS performed at a blues festival in 2009, they hit a high of 136 dB, before a festival official notified a sound engineer to turn down the volume. Guidelines or rules vary by country, and many diverge from the WHO recommendations.
Being aware that NIHL can lead to communication difficulties, tinnitus, distorted or muffled hearing, and other issues is the first step in prevention. The National Hearing Conservation Association suggests that people exposed to high levels of noise limit their risk through use of a personal hearing protection device, increase their distance from the source, and take quiet breaks to reduce overall exposure. Here are some additional tips from the CDC:
Last but not least, if you experience any signs of NIHL or are concerned about exposure and potential hearing loss, schedule a hearing evaluation with a licensed hearing care professional as soon as possible.
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