Hidden hearing loss and how it is often missed in tests

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For decades, scientists have assumed that the parts of our ears most susceptible to noise-induced hearing loss are the tiny hairs on our cochlea, deep in our ears, which vibrate when sound waves meet the sides of our ears. head. When these get damaged, it is as if someone has turned down the volume on the world and you might not hear the sounds even in the silence of a library.

Some patients may have complained that they could not, for example, hear the referee during a Little League game, but as long as their hair cells were intact and they could hear in a quiet test room. , doctors often could not find anything wrong. In 2009, however, armed with new imaging technology capable of looking beyond these hair cells, researchers exposed mice to the sound levels of rock concerts, and looked for signs of deeper damage to the auditory system.

They discovered that the brain cells with which this hair communicates are even more fragile than the hair cells themselves; while the hair cells in the animals’ ears remained intact after the “gig”, their corresponding brain cells shriveled.

These brain cells form two main bundles of neurons that translate hair vibrations into chemical signals that our brains can interpret. One set responds to louder sounds and another responds to quieter sounds. Dr Maison explained that those set to loud noises are the most likely to be damaged first, leaving the one designed for softer inputs to take over. When this happens, if you are in a quiet space and your friend is whispering to you, you will have no problem understanding it. If you do decide to go to a party, however, this whisper-loving group of cells will be overwhelmed by the background noise and send a garbled, indecipherable message to your brain.

There’s no conclusive test for hidden hearing loss, but if you’re struggling to catch the conversation every time the brunch table has more than a few guests, you might have it. For the past five years, Dr Maison said his team has been working to develop and validate a series of tests like those performed by Ms Gendreau, but diagnostic criteria are not yet final and, as of yet, few. audiologists check for hearing loss.

Ms. Gendreau had a myriad of hearing exams and even an MRI before the recent trial with Dr. Maison. None detected their hidden hearing loss. “Each time it was disappointing,” she said.

In 2017, the Associated Press published a online test you can try it at home, but it cannot provide a diagnosis. Still, experts have said if you think you might have hidden hearing loss because you have trouble keeping up with conversations when there is background noise or you have persistent ringing in your ears, it’s worth it. worth a visit to the audiologist.

The researchers are testing therapies on animals they hope to help regenerate damaged nerve fibers, but currently there is no way to reverse the hidden hearing loss. If you are diagnosed, audiologists recommend strategies that can help you communicate better.

Rather than asking someone to repeat themselves harder, have them repeat themselves more slowly, Dr Sydlowski said. Speaking “more clearly is much more effective than speaking louder, which we all tend to do,” she said.

Another strategy recommended by Dr. Maison is to “make sure the background noise is behind your back”. If you’re in a crowded restaurant with a friend, have them sit against the wall while you face them.

This strategy works especially well if you have a directional microphone, which amplifies sounds directly in front of you but dampens sounds from the sides and back, Dr Ren said. Simply connect the microphone to your headset or hearing aid and point it at the person speaking.

You can also try a frequency modulation system, which Dr. Ren says wirelessly transmits your partner’s voice to your headphones or hearing aids. The difference between this and the directional microphone is that the former does not amplify sounds coming from a particular direction, it simply shortens the path of sound to your ear, limiting the opportunities for it to mingle with background sounds or reverberates on other surfaces.

If you have an iPhone or iPad that is running iOS 14.3 or newer operating system, there is a built-in tool called Live listening which can turn the device’s microphone into a listening device similar to a frequency modulation system that can send sounds to your hearing aids or certain types of headphones, like airpods. Just connect via Bluetooth and swipe your phone close to the person you want to hear.


Emma Yasinski is a freelance science and medical journalist. Her work has been published in Smithsonian Magazine, Discover Magazine, Kaiser Health News, and MedShadow.org.


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