For about six years now, scientists have been studying a phenomenon called hidden hearing loss. In research published in Nature Communications, scientists with the University of Michigan reported they are looking at a new unexpected cause for this type of hearing loss. Hidden hearing loss is also referred to as an auditory neuropathy. Sudden hearing loss or hearing loss from a loud noise as well as age related hearing loss occurs when the tiny cells on the hairs in the ear are damaged.
When the cells are damaged, they don’t regenerate. The other hair cells pick up the slack for a time, but eventually there won’t be enough to process sound properly and you will start to lose your hearing. Auditory neuropathy is a variety of hearing loss in which the outer hair cells in the cochlea, which is the shell-shaped organ in the inner ear, are present and functioning correctly. But the sound information is not being transmitted in a useable form to the auditory nerve and the brain.
Scientists from the University of Michigan found in their research that damage to certain cells that form the sheaths around nerves could be behind hidden hearing loss. The damaged cells regenerate, but the ability to faithfully transmit impulses which are then decoded by the brain into “sound” does not regenerate.
Another cause of hidden hearing loss could be damage to synapses. Think of a synapse as a bridge from one nerve cell to another. The synapses in the hair cells need to communicate with the nerves in the inner ear and the inner ear transmits impulses to the brain and the brain deciphers the impulse into a specific sound.
Exposing yourself to loud noise, either a loud single noise like someone setting off a firecracker next to your ear or target shooting without proper ear protection or even going to loud night clubs four or five times a week can damage and/or destroy the synapses.
University of Michigan research showed that testing in a quiet room at an audiologist’s office required only a few synapses to work to pick up sound. In a noisy environment, the ear needs all synapses firing correctly to sort out conversation from sound. If that doesn’t happen, understanding conversation can be difficult if not impossible.
Gabriel Corfas, a scientist based at the University of Michigan, notes children are at particular risk.
“Exposure to noise is increasing in our society, and children are exposing themselves to high levels of noise very early in life,” he says. “It’s clear that being exposed to high levels of sound might contribute to increases in hidden hearing loss.”
Corfas says individuals can have noise-related hearing loss that has been identified, and one of the issues associated with hidden hearing loss such as myelin loss and only one type of loss is being treated.
There are no treatments right now for hidden hearing loss, but Corfas says understanding the condition can lead to better additional research as well as help audiologists help their patients understand their hearing issues.
More than 48 million Americans have some type of hearing loss yet many wait years to get it treated. During that time, hearing loss worsens, but many don’t get treatment because they feel they should just “deal with it.” Let us get you back on the path of better hearing health. At Glendora Hearing Aids & Audiology, we can do a comprehensive hearing evaluation and help you with a strategy to get hearing treatment in the form of hearing aids if necessary and also help you protect your hearing health.