What Is Sensorineural Hearing Loss?

Key Takeaways

• Approximately 38 million people over 18 in the United States experience some form of hearing loss.
• Sensorineural hearing loss is caused by damage to the inner ear, either of the auditory nerve or hair cells in the cochlea.
• Sensorineural hearing loss (SNHL) is one of the most common types of age-related hearing loss.¹
• Hearing aids can improve hearing ability for the majority of people with SNHL.
• If you’re experiencing sensorineural hearing loss symptoms, it’s important to have your hearing checked either online or at a hearing care clinic.
• Treatment of hearing loss can lower the risk of other health problems and enhance your quality of life.

Hearing loss is experienced by people of all ages and cultures: The World Health Organization (WHO) estimates that hearing loss affects 1.5 billion people worldwide, almost 20% of the world’s population.² In the United States, nearly 38 million people over 18 have some degree of hearing loss.³

Sensorineural hearing loss, or SNHL, is one of the most prevalent types of hearing loss and can be caused by a number of factors.⁴ While SNHL can’t always be prevented or reversed, using hearing aids can significantly help.

In the past few decades, research has shown untreated hearing loss can increase the risk of multiple serious health conditions, like dementia and other types of cognitive decline, depression, social isolation, and falls.⁵ If you or someone you care for has symptoms of sensorineural hearing loss, read on to learn about your options for hearing testing and treatment.

What causes sensorineural hearing loss?

The term “sensorineural” is a combination of two words. “Sensori” refers to the cochlea, which is the sensory organ of the inner ear. “Neural” refers to the auditory nerve that transmits sounds from the ear to the brain. If the auditory nerve or hair cells in the cochlea are damaged, SNHL can result.⁶

But what initially causes the cell or nerve damage that leads to hearing loss? Some of the most common causes of sensorineural hearing loss are:⁷

• Aging: Presbycusis is the medical term for age-related hearing loss.⁸ It often comes on gradually and may not be noticed until it significantly impacts your daily life.
• Injuries: Head trauma can also damage the ear, resulting in short- or long-term hearing loss.
• Illnesses: Viruses,⁹ diabetes,¹⁰ and high blood pressure¹¹ are all common causes of hearing loss.
• Ménière’s disease: This disorder of the inner ear causes hearing loss, dizziness, tinnitus ⓘA condition that is often linked to hearing loss and causes constant or periodic ringing or buzzing in the ear, and a full feeling in the ear.¹²
• Medications: Certain medications, like some antibiotics, chemotherapy drugs used to treat cancer, and loop diuretics, may cause hearing loss in some cases.¹³
• Noise exposure: The Centers for Disease Control and Prevention (CDC) provides information on how long it takes for exposure to the following loud noises to cause temporary or permanent hearing loss:¹⁴
  • Gas-powered lawn equipment: Two hours
  • Motorcycles: 50 minutes
  • Subways, car horns, sports events: 15 minutes
  • Personal audio devices set at maximum volume, loud music venues: Five minutes
  • Barking or yelling in ear: Two minutes
  • Standing close to sirens: Less than two minutes
  • Fireworks: Less than two minutes

Symptoms of sensorineural hearing loss

If you or a loved one are experiencing sensorineural hearing loss, you may notice the following symptoms:¹⁵

• Difficulty understanding speech when spoken at a normal level
• Trouble distinguishing high-pitched sounds such as “sh” or “th”
• Trouble hearing and understanding conversations in noisy environments or when more than two people are talking
• Hearing better in one ear than the other
• Feeling that people’s voices are muffled, and they often need to repeat what they said
• Buzzing or ringing sounds in the ears (tinnitus)

Types of sensorineural hearing loss

Just as eyesight can vary between the right and left eye, hearing ability is often different in each ear.

Bilateral

Hearing loss that is somewhat even in both ears is called bilateral. The National Institute on Aging estimated that bilateral hearing loss is the most common type experienced by older adults.¹⁶

Unilateral

Unilateral hearing loss occurs when one ear can hear within the normal range, but the other ear has some degree of hearing loss.¹⁷ You may also see the term single-sided deafness, or SSD, which refers to one ear completely lacking hearing ability.¹⁸

Asymmetrical

The term asymmetrical hearing loss refers to hearing loss that occurs in both ears, but it’s greater in one ear than the other. The shape of the audiogram, which shows how loud you need various sound frequencies to be in order to hear them, may also look different for one ear than the other.¹⁹

Sudden sensorineural hearing loss

Sudden sensorineural hearing loss (SSNHL) is hearing loss that occurs within a 72-hour window due to sensorineural causes rather than a physical blockage (due to excess fluid or earwax, for example).²⁰ It can be caused by an injury, illness, or exposure to a loud noise, like gunfire or an explosion. Research shows COVID-19 may also increase the risk of SSNHL.²¹ When this type of hearing loss occurs, it’s considered a medical emergency.

Brian Murray, a hearing instrument specialist and workshop consultant for Alpaca Audiology in Raleigh, North Carolina, said that prompt treatment can make all the difference for people with SSNHL. “Sometimes hearing can be restored fully or partially depending on the cause and potential treatments. A lot of times patients will wait and then try to schedule a hearing test, and by that time it’s too late and the loss may be permanent.”

If you experience a sudden loss of hearing in one or both ears, go to the nearest emergency department for immediate medical attention.

Diagnosing sensorineural hearing loss

An audiologist at a hearing care clinic can conduct testing to diagnose your type and degree of hearing loss. Hearing instrument specialists can also evaluate hearing loss for the purpose of fitting and dispensing hearing aids.²² And if you’re unable to get to a hearing care clinic or simply want a general idea of how good your hearing is, you can take an online hearing screening.

In-person hearing exams

An in-person hearing exam at a hearing care clinic is a thorough assessment that takes about an hour and includes both a physical exam and several hearing tests.

Pure tone audiometry

Pure tone testing consists of several types of hearing tests that measure how well each ear can hear low, medium, and high sound frequencies.²³

• Air and bone conduction testing: Both of these types of sound conduction are measured to determine whether a person has SNHL, conductive hearing loss, or mixed hearing loss (a combination of both types). “Air conduction and bone conduction testing are both pure tone tests, which means you’re testing thresholds at specific frequencies. Conduction refers to the medium, so with air, you’re testing through headphones or inserts. With bone conduction, you’re using an oscillator to vibrate the bone,” said Murray.

Speech audiometry

Speech audiometry consists of several parts that when combined, provide an overall picture of any hearing deficits that may affect your understanding of speech and conversations.²⁴

• Speech reception threshold (SRT) testing: This part of the exam tests the lowest volume at which you can hear and understand speech.
• Speech discrimination testing: In this section, you’ll repeat words that are spoken to you to determine how well you understand speech.
• Speech in noise testing: This test determines how well you can hear and understand speech in the presence of background noise.

After your exam is complete, you’ll receive a graph called an audiogram with the results from your pure tone audiometry tests. It shows the lowest volume at which you can hear different sound frequencies half of the time in each ear.

Audiogram results can be used in the following ways:

• To serve as the basis for a hearing professional to program your prescription hearing aids
• To calculate your pure tone average (PTA) ⓘThe pure tone average is a measure of how loud a sound needs to be in order to hear it. It’s calculated by averaging a person’s hearing thresholds at 500 hertz, 1,000 hertz, and 2,000 hertz., or Hearing Number
• To track changes in your hearing ability over time

Online hearing screenings

A number of online hearing screenings are now available. Most of them are free and take less than five minutes to complete. Online screenings can’t be used for diagnostic purposes, but they’re a great way to get a general idea of your hearing ability.

The Hearing Number

The Johns Hopkins Cochlear Center for Hearing and Public Health has developed an easy method of monitoring your hearing health, similar to the way many people keep track of other health numbers such as blood pressure or cholesterol.

The Hearing Number is equivalent to the PTA from an audiogram.²⁵ If you haven’t had an audiogram, you can check your hearing and get your Hearing Number by installing the free Mimi Hearing Test app on your smartphone.

The app is currently available only for Apple devices. After a three-minute hearing check called the Pure Tone Threshold test, the Mimi app provides your audiogram and Hearing Number. You can also keep track of your hearing results over time.

We spoke with Frank Lin, MD, PhD, director of the Center for Cochlear Hearing and Public Health and an epidemiologist at Johns Hopkins University in Baltimore, Maryland, about Hearing Numbers. Lin said knowing your Hearing Number can help you get treatment for hearing loss if and when it happens. “[Hearing loss] is a natural progression that we all go through, but if you know your number you can act on it.”

How to treat sensorineural hearing loss

A variety of treatments are effective at treating SNHL and improving hearing ability. The most common mode of treatment is hearing aids.

Hearing aids

In years past, hearing aids didn’t always work well and often came with distracting effects, like whistling noises when being handled. But hearing aid technology and design have advanced greatly in the past two decades, and many modern hearing aids are built with high-tech features, like rechargeable batteries, Bluetooth connectivity, water resistance, and artificial intelligence for improved sound processing.

Types of hearing aids

Today, over-the-counter (OTC) hearing aids can be used by adults with mild to moderate hearing loss and start at around $200 per pair. You can also find more information on the most affordable hearing aids.

Prescription hearing aids can treat all degrees of hearing loss, from mild to profound. They generally cost at least $1,600 per pair but also include more features and customizability than OTC devices.

Specialized prescription devices, called contralateral routing of signal (CROS) hearing aids, are also available for people with unilateral hearing loss. They work by sending sound frequencies picked up in the nonfunctional ear to a hearing aid worn in the functional ear for processing. ²⁶

How do hearing aids work?

Most OTC and prescription hearing aids are called air-conduction hearing aids, and they work by amplifying sound frequencies using air vibrations. The amplified sound is then sent through the ear canal to the middle and inner ear.²⁷

Bone-conduction hearing aids

Due to their different design and sound-processing mechanism, bone-conduction hearing aids can be surgically placed, worn on a headband, or placed directly on the skin. They amplify sound by vibrating bones in the skull, which then stimulates the inner ear.²⁸

People with outer or middle ear problems may benefit from bone-conduction hearing aids. They can also be used to treat the following conditions:

• Unilateral hearing loss
• Sudden sensorineural hearing loss
• Ear canal or middle ear malformations

Cochlear implants

Cochlear implants are surgically implanted devices that can be helpful for people with unilateral hearing loss, one-sided deafness, or other conditions that can’t be successfully treated with traditional hearing aids.²⁹ Because cochlear implants send signals directly to the auditory nerve for processing in the brain, they bypass the need for involvement by the inner ear.

Auditory training

Wearing hearing aids can help your ears take in more sound, but your brain may still have trouble making sense of that sound, especially if you’ve had hearing loss for years but only recently started using hearing aids. The reason for this is that when hearing loss goes untreated, the brain pathways that normally process sound begin to die. Over time, they even get recruited to process signals from your other senses, such as sight.³⁰

Wearing hearing aids can cause positive changes in the brain characterized by the reactivation of those auditory pathways, and auditory training can help by training your brain to make sense of the sounds around you, including conversations.³¹

Auditory training apps and computer programs often resemble video games and can be played on a laptop, smartphone, or other device. This type of hearing therapy is still fairly new, and it’s not routinely discussed during hearing exams. But you may find the combination of auditory training and consistent hearing aid use helpful for improving understanding of sounds in your environment.

Tools and strategies for better communication

Making a few adjustments in how you communicate and using specialized audio equipment can also be helpful in your journey to better hearing.

Good communication practices

The Hearing Number website lists steps you can take to help improve communication and enjoy the time you spend with family and friends. Try the following ideas:

• Using closed captioning on television and computer videos
• Optimizing the audio output on your cell phone
• Choosing quiet spaces rather than loud rooms for conversations when possible
• Standing close and using eye contact when having a conversation
• Explaining what you missed and asking the person to repeat it when needed
• Using VoIP (voice-over protocol) services, like FaceTime or Google Voice, rather than the phone for better sound quality

In many states, residents can get an internet-based Captel phone free of charge if they have a confirmation from a doctor or audiologist stating they have hearing loss. These phones allow you to hear and read phone conversations at the same time. Voice messages are also recorded on the screen, so you can read them later.

Is sensorineural hearing loss permanent?

SNHL is usually permanent. Once the hair cells of the inner ear are damaged or lost, they can’t be repaired. The good news is that hearing aids can greatly improve hearing ability in the majority of people with SNHL.

Conductive vs. sensorineural hearing loss

SNHL is one common type of hearing loss, but there’s also a second type, called conductive hearing loss. This condition occurs when sounds can’t travel from the middle or outer ear to the inner ear.³²

Causes of conductive hearing loss include:

• Earwax buildup
• Foreign objects stuck in the ear canal
• A hole in the eardrum
• Fluid in the ear, which can build up due to allergies or ear infections
• Bone malformations
• Congenital defects in the ear

Treatment for conductive hearing loss often involves procedures to remove the obstruction or otherwise address the cause of hearing loss.

Murray said that while the ultimate goal is always to correct an underlying condition affecting a patient’s hearing, “There are certain cases where conductive losses can’t be medically treated, or they require surgery or intervention that a patient doesn’t want to go through with.” In those cases, hearing aids can still help by amplifying sounds entering your ear canal.

Our Reviews Team interviewed Jacquelyn C. J. Lovitt, AuD, co-founder of Capital Institute of Hearing and Balance in Silver Spring, Maryland, for more information about treatment options for different types of hearing loss.

How to prevent hearing loss

The NIDCD recommends the following steps to help protect your hearing and prevent or delay hearing loss:³³

• Wear hearing protection when you’re near loud equipment, at music venues, or in other noisy environments.
• Put distance between yourself and loud noises when possible.
• Use caution when wearing hearing amplifiers or earbuds to listen to music, and don’t turn the volume up past a safe level (generally less than 60% of your headphones’ strength).
• Get your hearing checked regularly. Johns Hopkins Medicine advises people to get an annual hearing exam as part of their routine physical each year.³⁴

Bottom line

Hearing health research and technology have greatly advanced in the past 20 years, and there are now a variety of solutions to help people with hearing loss.

Sensorineural hearing loss can significantly affect your quality of life and health. Getting help for your hearing with hearing aids, compensatory strategies for communicating, and other forms of treatment is crucial for your overall well-being.

Have questions about this review? Email us at reviewsteam@ncoa.org.

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