By Vicky Chan

April 25 is International Noise Awareness Day, an annual, vital reminder to take a stand against noise exposure and to spread awareness about the underestimated threat of noise-induced hearing loss (NIHL). Seemingly harmless rhythms, roars, and blasts heard daily from music, trains, and machinery are, in fact, among the top offenders of NIHL.

Noise-induced hearing loss (NIHL) progressively occurs after chronic exposure to loud sounds. The frequency and intensity of the sound level, measured in decibels (dB), increases the risk of NIHL. Gradual hearing loss can result from prolonged contact with noise levels of 85 dB or greater, such as heavy city traffic. Noises of 110 dB or more, like construction (110 dB), an ambulance (120dB), or the pop of firecrackers (140-165 dB) can damage one’s hearing in a minute’s time.

NIHL is the only type of hearing loss that is completely preventable, yet billions of individuals endanger themselves daily. Over 1.1 billion young adults ages 12 to 35—an age group that frequently uses headphones to listen to music—are at risk. Already, an estimated 12.5% of young people ages of 6 to 19 have hearing loss as a result of using earbuds or headphones at a high volume. A device playing at maximum volume (105 dB) is dangerous, so exposure to sounds at 100 dB for more than 15 minutes is highly discouraged.

Most major cities around the world have transit systems that put commuters in contact with sounds at 110 dB. BBC News found that London’s transit systems can get as loud as 110 dB, which is louder than a nearby helicopter taking off. The sound levels of some stations exceed the threshold for which occupational hearing protection is legally required. New York City has one of the largest and oldest subway systems in the world where 91% of commuters exceed the recommended levels of noise exposure annually. In a study on Toronto’s subway system, 20% of intermittent bursts of impulse noises were greater than 114 dB.

People who work in certain fields are more vulnerable to NIHL than others. Professional musicians, for instance, are almost four times as likely to develop NIHL than the general public. Military personnel, who are in extremely close proximity to gunfire and blasts, are more likely to return home from combat with hearing loss and/or tinnitus than any other type of injury. And airport ground staff are surrounded by high-frequency aircraft noises at 140 dB. In all of these professions, the hazard of NIHL can be significantly mitigated with hearing protection.

NIHL is permanent. Increased exposure to excess noise destroys the sensory cells in the inner ears (hair cells), which decreases hearing capacity and leads to hearing loss. Once damaged, the sensory cells cannot be restored. To find a solution, Hearing Health Foundation’s (HHF) Hearing Restoration Project (HRP) conducts groundbreaking research on inner ear hair cell regeneration in hopes of discovering a life-changing cure.

Nearly three-quarters of those who are exposed to loud noises rarely or never use hearing protection. It is our dream that someday, NIHL will be reversible as a result of the HRP. Until then, to make noise safer, HHF advises protection by remembering to Block, Walk, and Turn. Block out noises by wearing earplugs or protective earmuffs. Walk away or limit exposure to high-levels of noises. Turn down the volume of electronic devices.