Hearing loss due to noise
- Article
- 2021-03-02
What is noise hearing loss?
Every day we experience sound in our environment, such as the sounds of television and radio, household appliances and traffic. Normally these sounds are at safe levels that will not damage our hearing. But sounds can be harmful if they are too loud, even for a short time, or if they are both loud and long-lasting. These sounds can damage sensitive structures in the inner ear and cause noise-induced hearing loss (NIHL).
NIHL can occur immediately or it can take a long time to be noticeable. It can be temporary or permanent, and it can affect one ear or both ears. Even if you cannot see that you are damaging your hearing, you may experience problems with hearing in the future, such as not being able to hear other people when they are talking, especially on the phone or in a noisy room. Regardless of how it may affect you, one thing is for sure - noise-induced hearing loss is something you can prevent.
Who Is Affected by NIHL?
Exposure to harmful noise can occur at any age. People of all ages, including children, teens, young adults, and the elderly, can develop NIHL. Based on a 2011-2012 CDC study that included hearing tests and interviews with participants, at least 10 million adults (6 percent) in the US under the age of 70 - and perhaps as many as 40 million adults (24 percent) - have characteristics of their hearing. test suggesting hearing loss in one or both ears from exposure to loud noise. Researchers have also estimated that as many as 17 percent of teens (ages 12 to 19) have hearing test features that indicate NIHL in one or both ears (Pediatrics 2011 (link is external)), based on data from 2005-2006.
What Causes NIHL?
NIHL can be caused by a single exposure to an intense "impulse sound", such as an explosion, or by continuous exposure to loud sounds for an extended period of time, such as sound generated in a woodworking shop.
Recreational activities that could put you at risk for NIHL include shooting and hunting, riding a snowmobile, listening to high volume MP3 players through earphones or headphones, playing in a band, and attending loud concerts. Harmful noises in the home can come from lawn mowers, leaf blowers and woodworking tools, among others.
Sound is measured in units called decibels. Sounds with or below 70 A-weighted decibels (dBA), even after prolonged exposure, are unlikely to cause hearing loss. However, prolonged or repeated exposure to sounds of 85 dBA or higher can cause hearing loss. The louder the sound, the shorter it takes for NIHL to occur.
Here are the average decibel values of some known sounds:
- Normal conversation
60-70 dBA - Cinema
74-104 dBA - Motorcycles and dirt bikes
80-110 dBA - Music through headphones at maximum volume, sporting events and concerts
94-110 dBA - Sirens
110-129 dBA - Fireworks show
140-160 dBA
Your distance from the source of the sound and the length of time you are exposed to the sound are also important factors in protecting your hearing. A good rule of thumb is to avoid sounds that are too loud, too close, or too long.
How can noise damage our hearing?
To understand how loud sounds can damage our hearing, we need to understand how we hear. Hearing relies on a series of events that turn sound waves in the air into electrical signals. Our auditory nerve then carries these signals to the brain through a complex series of steps.
- Sound waves enter the outer ear and travel through a narrow passage called the ear canal that leads to the eardrum.
- The eardrum vibrates from the incoming sound waves and sends these vibrations to three small bones in the middle ear. These bones are called the hammer, anvil, and stirrup.
- The bones in the middle ear couple the sound vibrations from the air to fluid vibrations in the cochlea of the inner ear, which is shaped like a snail and filled with fluid. An elastic partition runs from the beginning to the end of the cochlea, splitting it into an upper and lower part. This partition is called the basilar membrane because it serves as the base, or ground floor, on which the main auditory structures sit.
- Once the vibrations cause the fluid to enter the cochlea gWhen wrinkling, a traveling wave forms along the basilar membrane. Hair cells - sensory cells that sit on top of the basilar membrane - ride the wave.
- As the hair cells move up and down, microscopic hair-like protrusions (known as stereocilia) that sit on top of the hair cells collide with an overlying structure and bend. Bending opens pore-like channels located at the ends of the stereocilia. When that happens, chemicals flood into the cell and create an electrical signal.
- The auditory nerve carries this electrical signal to the brain, which translates it into a sound that we recognize and understand.
What Are the Effects and Signs of NIHL?
If you are exposed to loud noise for a long time, you may slowly lose your hearing. Because the damage from noise exposure is usually gradual, you may not notice or ignore the signs of hearing loss until they become more apparent. Over time, sounds can become distorted or muffled and you may find it difficult to understand other people when they are talking or when you need to turn up the volume on the TV. The damage from NIHL, coupled with aging, can lead to hearing loss so severe that you need hearing aids to amplify the sounds around you so that you can hear better, communicate and participate more in everyday activities.
NIHL can also be caused by extremely loud bursts of sound, such as gunshots or explosions, which can rupture the eardrum or damage the bones in the middle ear. This kind of NIHL can be immediate and permanent.
Loud exposure to noise can also cause tinnitus - a buzzing, buzzing, or roar in the ears or head. Tinnitus can diminish over time but can sometimes persist constantly or intermittently throughout a person's life. Hearing loss and tinnitus can occur in one or both ears.
Sometimes exposure to impulse or continuous loud noise causes a temporary hearing loss that disappears 16 to 48 hours later. However, recent research suggests that while the hearing loss appears to disappear, long-term hearing damage can still occur.
Can NIHL be prevented?
NIHL is the only type of hearing loss that is completely preventable. Understanding the dangers of noise and how to practice good hearing health can help protect your hearing for a lifetime. Here's how:
- Know which sounds can cause damage (those of 85 dBA or higher).
- Wear earplugs or other protective devices when involved in a loud activity (activity-specific earplugs and earmuffs are available at hardware and sporting goods stores).
- If you can't reduce the noise or protect yourself from it, get away from it.
- Be alert for dangerous noises in the environment.
- Protect the ears of children who are too young to protect their own.
- Make family, friends and colleagues aware of the dangers of noise.
- If you think you have hearing loss, have your hearing tested.
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