9 months ago
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We know that blasting tunes at volume, working in excessively noisy environments, and even gaming can damage our hearing, but how exactly does this happen?
Scientists now have a better idea about that, and have also discovered a potential way to prevent it.
A team from the University of Pittsburgh used tests on mice to establish that loud noises were linked to spikes in zinc levels in the inner ear, both in terms of quantity and how widely it was spread. It's that spread of zinc that appears to harm ear cells and disrupt communication between them.
The researchers also discovered that certain drugs could work as sponges to mop up the excess zinc and restore or protect hearing. Eventually, we might one day be popping tablets ahead of rock concerts to keep our ears safe.
"These results highlight zinc signaling as a potential target for preventing and mitigating noise-induced hearing loss," write the researchers in their published paper.
Along with its own special 'loading' protein, zinc is found in specific areas of healthy cochlear hair cells and the spiral limbus. Exposure to loud noises causes an over-abundance of these two chemicals throughout the cells, scattered like cups through the house the morning after a big party.
Using genetic tweaks and the administration of drug compounds, the researchers were able to reduce these zinc levels in the mice, restoring hearing loss to some extent and providing some protection against exposure to noises at a loud volume.
There's a lot more work to be done before something suitable for humans can be cleared as safe and effective, but the hope is that treatments can be developed to be applied before or after exposure (in an emergency room, for example).
"Genetic or pharmacological disruption of zinc signaling promotes cochlear recovery after noise trauma," write the researchers.
We know that prolonged exposure to loud sounds can cause hearing loss, and that it's a common problem. Around 1.5 billion people across the world live with some kind of hearing loss, according to the World Health Organization.
It's why countries have laws about wearing ear protectors on construction sites, and why many smartphones will now warn you if you're trying to push the volume of your music pumping through your headphones to a higher level than your ears can take.
Over time, problems such as tinnitus (incessant ringing in the ears) can develop, but this new study now brings with it some important revelations about what exactly is going on – and how we might be able to stop these debilitating effects.
"Noise induced hearing loss impairs millions of lives but, because the biology of hearing loss is not fully understood, preventing hearing loss has been an ongoing challenge," says otolaryngologist Thanos Tzounopoulos from the University of Pittsburgh.
The research has been published in PNAS.
