Study reveals how loud noises can damage hearing


It is common knowledge that loud sounds can damage our hearing. Now, a new study by researchers from the University of Leicester in the UK sheds new light on how this happens, paving the way for new prevention and treatment strategies for hearing loss and tinnitus.

According to the Hearing Health Foundation, approximately 26 million Americans have high-frequency hearing loss as a result of exposure to loud noises at work or during leisure activities, such as listening to loud music.

The research team, including Dr. Martine Hamann, a lecturer in neurosciences at the University of Leicester, notes that many individuals listen to loud music without realizing it can affect their hearing later in life.

“People who suffer from hearing loss have difficulties in understanding speech, particularly when the environment is noisy and when other people are talking nearby,” says Dr. Hamann.

She notes that understanding speech is dependent on fast transmission of auditory signals through the auditory nerve – the nerve that transports sound waves from the cochlea of the inner ear to the brain.

But previous research has shown that after exposure to loud sounds, transmission of these auditory signals slows down, leading to hearing loss.

Dr. Hamann says it is important to determine the mechanisms behind this. “Understanding these underlying phenomena means that it could be possible to find medicines to improve auditory perception, specifically in noisy backgrounds,” she adds.

Thinning of myelin coat ‘primary cause of hearing loss in response to loud sounds’

Past studies have shown that loud noises can narrow the myelin coat that protects the auditory nerve.

Furthermore, loud sounds have been shown to elongate myelin sheath gaps, more commonly known as nodes of Ranvier, which auditory signals jump between in order to process sound.

But Dr. Hamann says that these findings pose a question: is reduced auditory signaling following exposure to loud sounds a result of the thinning of the myelin coat or the elongation of nodes?

For their study, recently published in the journal Frontiers in Neuroanatomy, the researchers used computational modeling to simulate thinning of the myelin coat around the auditory nerve and lengthening of nodes. They then assessed how each of these changes affected auditory signaling through the auditory nerve.

The team found that hearing loss as a result of exposure to loud noises is primarily caused by the thinning of the protective myelin coat surrounding the auditory nerve, while changes to the nodes only have a small effect on hearing loss.

Commenting on the findings, Dr. Hamann says:

“We have come closer to understanding the reasons behind deficits in auditory perception. This means that we can also get closer to target those deficits, for example by promoting myelin repair after acoustic trauma or during age-related hearing loss.”

The team says their findings may help uncover prevention strategies for hearing loss and tinnitus (ringing in the ears) and could even lead to cures for the conditions.

They now plan to test drugs that trigger myelin repair to see if they can restore hearing following hearing loss.

Medical News Today recently reported on a study from Brigham and Women’s Hospital in Boston, MA, which suggests women who drink more coffee are less likely to develop tinnitus.




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