According to the World Health Organization, hearing loss affects nearly 1.5 billion people globally.
OSHA estimates that nearly 22 million workers in the United States are exposed to occupational noise that could damage their hearing and has implemented a hearing conservation program to help mitigate hearing loss among workers.
Complicating these risk factors are recreational activities and pastimes that increase our risk of noise pollution and significantly impact the health of the human ear.
Simply attending a rock concert, for instance, can expose our ears to sound levels that aren’t safe and can significantly impact our hearing.
Noise-induced hearing loss is a condition that affects important structures in your ear and impairs your ability to hear as well as you used to.
We’ll discuss how the ear works, what causes noise-induced hearing loss, the symptoms, and treatment options.
We’ll also talk about factors that increase your susceptibility to this type of hearing loss.
How Do We Hear Sound?
To fully understand noise-induced hearing loss, you need a basic understanding of how hearing occurs. For this, we begin a short anatomy lesson.
Sound waves enter the outer ear and travel down the ear canal to the eardrum.
These sound waves cause the eardrum to vibrate against three small bones in the middle ear: the malleus, incus, and stapes.
These bones amplify the vibrations and send them to the cochlea, a snail-shaped structure filled with fluid and sits in the inner ear.
Structures inside the cochlea turn the vibrations into electrical signals, which the auditory nerve carries to the brain. The brain interprets these signals as the sounds we hear.
The Structures of the Cochlea
There are two important structures inside the cochlea that help change the sound waves into electrical signals:
- The basilar membrane. This membrane acts like a base for other structures inside the cochlea, supporting them and helping divide the cochlea into two parts. This membrane is vital to the health of the second important structure, the hair cells.
- Hair cells. Hair cells, also known as sensory cells, located on the top of the basilar membrane ripple from the vibrating fluid in the cochlea and form electrical signals.
These tiny hair cells are vital to the hearing process, and each person is born with a limited amount.
Typically, each person has approximately 15,000 of these cells in each ear.
What Is Noise-Induced Hearing Loss?
Noise-induced hearing loss, also known as NIHL, is caused by damage to structures in the inner ear that make hearing more difficult.
This damage comes from noise exposure to sounds much louder than normal conversation or ambient noise.
These sounds usually come from non-human sources, like machines, tools, vehicles, explosives, or sound amplifying devices.
How Loud Is Too Loud?
Sound is measured in decibels. Most sounds under 70 decibels are considered safe for the delicate structures in the ear.
Sound over 85 decibels is considered dangerous and can lead to NIHL.
Consider the decibel levels of these common sounds to give you an idea of how loud certain sounds are.
- Conversations are around 60 dB
- Vacuum cleaners and hair dryers are around 80 dB
- Gas-powered leaf blowers and lawn mowers are 105 to 1105 dB
- Sirens are around 120 dB
- Jet engines (from a distance of 100 yards) are around 135 dB
- Gunshots are around 140 dB
NIHL is sensorineural hearing loss that can result from loud sounds, diseases, genetic disorders, or brain injuries.
What Part of the Ear Is Damaged by Noise-Induced Hearing Loss?
The structures inside the inner ear that NIHL most commonly damages are the basilar membrane and the sensory hair cells.
The hair cells, in particular, are easily damaged and destroyed.
Unlike the auditory hair cells in some animals, human auditory hair cells do not regenerate.
This means that hearing loss caused by NIHL is often permanent.
What Causes Noise-Induced Hearing Loss?
There are many sounds that cause NIHL, and there are several ways you might experience this type of hearing loss.
Immediate Noise-Induced Hearing Loss
Noise-induced hearing loss can be immediate, caused by impulse sounds. This refers to hearing loss from exposure to a single loud noise. An explosion, for instance, could cause this type of NIHL.
Most of the time, NIHL happens gradually over a long period.
This type of NIHL is progressive and very common.
People commonly hear these types of hazardous noises in their work environments.
Working on a firing range, on a construction site, or on any job that requires power tools can be a source of dangerous noise.
Landscapers who regularly use equipment like lawn mowers and leaf blowers are also more susceptible to developing NIHL.
Hobbies and pastimes can also place you at a higher risk of developing NIHS.
Loud music, motorcycles, snowmobiles, off-road vehicles, loud cars, and any type of noisy environment that exposes you to excessive noise can lead to NIHL.
What Are the Symptoms of Noise-Induced Hearing Loss?
It can take up to 10 years of continual exposure to harmful noises before you realize your hearing is impaired.
Symptoms of noise-induced hearing loss include:
- Inability to hear high-frequency sounds
- Observing that you can no longer hear as well as you once could
- Mumbled or muffled speech
- Ringing in the ears, also known as tinnitus
- Pressure in the ear, or feeling like there’s something inside your ear
These symptoms can last for a few minutes, hours, or even days.
Even if your hearing returns to “normal,” cells in your cochlea may still be damaged and destroyed.
Diagnosing Noise-Induced Hearing Loss
A healthcare provider or audiologist will diagnose NIHL by giving you a simple hearing test.
Auditory testing usually involves an audiogram, which shows the frequencies a person can and cannot hear.
This simple, minimally invasive test includes wearing headphones and responding when you hear a sound in either ear.
Treatment Options for Noise-Induced Hearing Loss
The biggest treatment for NIHL is prevention.
Even if you’ve already developed some hearing loss, the most important thing you can do for your hearing is to protect it against further loss.
The American Academy of Audiology’s “Turn It To The Left” campaign focuses on helping prevent hearing loss caused by sound, which has become more prevalent among pediatric patients.
Preventing further hearing damage involves using smart judgment when considering the type of noise you’ll hear and using hearing protection devices to ensure you don’t expose your ears to unsafe noise levels. These include:
- Hearing protection headphones (designed to block out unsafe noise levels)
These devices amplify sounds (safely) into the inner ear, helping you hear better.
Hearing aids can dramatically improve the lifestyle of someone who has experienced hearing loss. Numerous low-profile hearing aid types make it virtually impossible to see a hearing aid.
Assistive Living Devices (ALDs)
These are short-term hearing assistance devices that help block out background noise that can impair your hearing.
They also make it easier for you to focus on sound in the distance (like in an auditorium) or overcome poor acoustics.
A Note About Permanent Hearing Loss
Hearing loss can be permanent or temporary. Temporary hearing loss, also known as a temporary threshold shift, can occur from causes like infections, a buildup of earwax, certain prescription medication, or short-term exposure to loud noise (like when your ears ring after a firework explodes).
According to the Centers for Disease Control and Prevention, hearing loss caused by noise (NIHL) is almost always permanent because of the damage to the hair cells in the ear.
Permanent hearing loss is known as permanent threshold shift.
If your hearing loss becomes so severe you cannot hear most sounds, you may benefit from treatment options like cochlear implants, which bypass the damaged portions of the ear and send soundwaves directly to the auditory nerve.
Protect Your Hearing
Your hearing, much like your vision, is precious.
Hair cells within your ears help change sound waves into electrical signals that travel to your brain via the auditory nerve. Without these cells, your hearing becomes impaired.
While some hearing loss like age-related hearing loss is not as avoidable, exposure to loud sounds (considered sound over 70 decibels) can damage and destroy these cells.
Protecting your hearing is as simple as making smart decisions about noisy environments and using appropriate hearing protection when necessary.
To find out more, check out the USA Rx blog, where you can locate information on hearing, hearing loss, and other treatment options to help you lead a full and satisfying life regardless of your current hearing threshold.