What is hidden hearing loss?

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Contribution by Temma Ehrenfeld
Last update 2021-11-22T00: 00: 00-06: 00

For most of her adult life, Alice *, a psychologist in New York City, had difficulty hearing, especially in noisy places. Yet when she sought professional help, she passed her hearing test with flying colors.

Alice, who now avoids crowded restaurants and parties, most likely suffers from what’s called “hidden hearing loss,” a brain problem that hearing tests aren’t designed to detect. For this reason, it is not a well understood condition.

What is hidden hearing loss?

“Hidden” hearing loss is defined as hearing loss that is not detectable on standard hearing tests, which focus on problems in the ear, but not on the nervous system.

No one knows exactly how many people have a hidden ear gloss. But in a to study Out of more than 100,000 patient records over a 16-year period, about 10% of the patients who visited the Massachusetts Eye and Ear Audiology Clinic had a normal audiogram, like Alice, despite their complaints.

Signs of hidden hearing loss

There is no set of established guidelines for diagnosing hidden hearing loss, but some things to look out for include:

  • A strong feeling that you have hearing loss, even after having a hearing test
  • A preference for silent settings for conversations
  • Feeling easily distracted or unable to concentrate in noisy environments
  • Hearing people poorly

Hidden hearing loss test

If you’ve been told that a standard “pure tone” hearing test has shown no signs of hearing loss, don’t give up. When you have hidden hearing loss, you probably need more testing to help find out what’s going on.

Sometimes hidden hearing loss can be revealed using a rapid “words in noise” or “sentences in noise” test, which involves listening to recorded segments of speech in increasingly noisy environments. According to a item in the Hearing Journal, all of the following tests may also be used by an audiologist to help identify hidden hearing loss and rule out other causes:

  • otoscopy
  • tympanometry
  • acoustic reflexes
  • otoacoustic emissions diagnostic distortion product
  • extended high frequency audiometry
  • air, bone and speech reception test
  • brainstem auditory response (ABR) test

What is going on in the brain?

When we hear, movements of the cilia or hair cells in the inner ear send signals to the auditory nerve, also known as the vestibulo-cochlear nerve or eighth cranial nerve. These signals must pass through synapses, which are the vital junctions between nerve cells. Learn more about how we hear.

Ordinary hearing loss results from damage to hair cells or the nerve. Hidden hearing loss often occurs due to the loss of synapses between the two. The signal arrives incomplete, so there is a lack of information we need to interpret the words. Medically, this is sometimes called “cochlear synaptopathy,” although not all people with invisible hearing loss have synaptopathy.

“Hidden” hearing loss is defined as hearing loss that is not detectable on standard hearing tests, which focus on problems in the ear.

Audiologists have been describing patients like Alice for years. In 2009, a watershed to study in mice documented that loud noises could specifically destroy synapses. In the study, mice were forced to put up with a noise of 100 decibels – about the same level as with a lawn mower – for two hours. Later, the team found that although the hair cells in the mice survived, half of their synapses had disappeared.

Humans with lost synapses can still hear the beep during a hearing test, even at a low volume, which confuses a person with cell or nerve damage.

What are the causes of hidden hearing loss?

Noise nuisance and aging combine to make the problem worse. “Most researchers believe that prolonged exposure to even low-intensity noise can cause hidden hearing loss and most agree that the aging hearing system reveals this problem. We lose some synapses as we age, ”said Dr. Catherine Palmer, director of audiology and hearing aids at the University of Pittsburgh Medical Center.

Another possible cause, reported in 2017, could be problems with the cells that make myelin, a substance that isolates neural axons (brain cells) in the ear. Autoimmune disorders like Guillain-Barré syndrome, linked to food poisoning, influenza, hepatitis and Zika virus, attack myelin.

Different from ADHD and auditory processing disorder

Note that hidden hearing loss can be confused with Attention Deficit Hyperactivity Disorder (ADHD), which happened to Alice after taking a hearing test. It is also not the same as “central auditory processing disorder,” which is often diagnosed in children and occurs at a different level of the brain.

Experimental tools to detect hidden hearing loss

The Massachusetts Eye and Ear team have developed two tests to detect hidden hearing loss. The first measures electrical signals coming from the surface of the ear canal to understand how well they encode subtle and rapid fluctuations in sound waves. For the second test, participants wear glasses that measure changes in the diameter of their pupils while listening to speech in noise. Our students reflect the effort it takes to understand during a task.

When the team tried the tests on 23 volunteers with clinically normal hearing, their ability to follow a conversation with background babbling varied widely. The two tests combined predicted which people would have difficulty.

What it’s like to live with hidden hearing loss

Alice’s story is emblematic. She remembers once when she was in a group of three in a 15-person room, a reunion of her classmates. “I was right next to them and couldn’t hear a single word,” she said.

“I finally asked a [of them] go into a room with only a few people, and we were seated but I had to bring my chair closer and lean forward, ”Alice explained. “I said, ‘I’m sorry if I feel like I’m sitting on your lap. “”

She’s been dealing with the problem for years. When she was 20, she saw an audiologist who told her her hearing was normal, but suggested that she might have an “attention problem”.

Yet she can hear a whisper in a quiet place; she only has difficulty understanding what audiologists call “speech in noise”, conversation in a group or in noisy places. As the background noise in the restaurants grew louder, Alice looked for quiet restaurants. The big parties “have lost their appeal,” she said. She became a therapist.

“It’s a wonderful profession because it’s just me and another person and if I can’t hear them I say What?”

She had her second audiogram a year ago, decades after the first. Again, her hearing was normal and the audiologist explained her difficulties as an “auditory processing problem”. Alice took her audiogram to a Costco hearing aid service, but was told that because her hearing was in the normal range, the store would not sell her a device.

Treatment of hidden hearing loss

There is no straightforward treatment, although research is ongoing to find drugs that would prompt neurons to develop new synapses. In cases where there is at least mild or mild hearing loss, people will benefit from advanced hearing aids with “speech in noise” settings. These use directional microphones to pick up the signal in front of you and reduce the sound behind you or to your sides. You can also place a microphone near the signal you need to hear and wear a Bluetooth receiver or hearing aid in your ear.

Look for a hearing care professional who is familiar with hidden hearing loss. They can help you decide if any of the available listening assist devices can help, such as a personal FM system or a mobile app that can caption a live conversation. Be sure to take advantage of the listening assistive devices required by the ADA in theaters, places of worship, airports and other public spaces.

At home and in your social life, it will be easier for you to be in quieter places. Eat earlier in the evening when restaurants are quiet, choose restaurants with carpeted floors and no bars, or sit in a booth. Get to class early so you can sit near the front. At gatherings, feel free to make smaller groups and lean over, even if it feels like you are sitting on someone’s lap.

Finally, try not to deny the problem and step back. Be aware of how this affects your mental state. Like any type of hearing loss, hidden hearing loss “can have an effect on your psyche, creating avoidance behavior and social anxiety,” Alice noted. “You might not even know it. ”

* To protect Alice’s privacy, we have used a different name.


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