Listening to loud music has been shown time and time again to affect hearing in a negative way. The damage becomes more pronounced with age, leading to difficulties in understanding speech. A new analytic study by researchers at University of Leicester examined the cellular mechanisms that underlie hearing loss and tinnitus triggered by exposure to loud sound.
Music to your ears or ...
Dr Martine Hamann, Lecturer in Neurosciences at the University of Leicester, said: “People who suffer from hearing loss have difficulties in understanding speech, particularly when the environment is noisy and when other people are talking nearby.
“Understanding speech relies on fast transmission of auditory signals. Therefore it is important to understand how the speed of signal transmission gets decreased during hearing loss. Understanding these underlying phenomena means that it could be possible to find medicines to improve auditory perception, specifically in noisy backgrounds.”
There are tens of millions of people all over the world that are affected by hearing loss, with grave social consequences. Often enough, these people become isolated from friends and family because of their impaired ability to understand speech. Everybody has an annoying great uncle that incessantly asks 'how's school' or 'when are you getting married', before exclaiming 'what, what, what?!' Hearing loss isn't confined to old age anymore, though, once with the advent of high power speakers and headphones. It's amazing to me how some people behave so unconsciously and nudge their heads straight in a 4000W speaker for hours. You've seen them at festivals.
In a survey of 2,711 festival-goers in 2008, 84% said they experienced dullness of hearing or ringing in the ears after listening to loud music.
"These are the first signs of hearing damage," says Donna Tipping from Action on Hearing Loss charity.
"The next morning or a couple of days later, your hearing may gradually return to normal but over time, with continued exposure, there can be permanent damage."
Donna says the risk of damage to hearing is based on how loud the music is and how long you listen to it for.
"If you can't talk to someone two metres away without shouting, the noise level could be damaging," she says.
Previous research showed that following exposure to loud sounds, the myelin coat that surrounds the auditory never becomes thinner. The audio signal travels in jumps from one myelin domain to the other. When exposed to lound sound, these domains, called Nodes of Ranvier, become elongated. It wasn't clear however if the hearing loss was due to the actual change of the physical properties of the myelin or is it due to the redistribution of channels occurring subsequent to those changes.
“This work is a theoretical work whereby we tested the hypothesis that myelin was the prime reason for the decreased signal transmission. We simulated how physical changes to the myelin and/or redistribution of channels influenced the signal transmission along the auditory nerve. We found that the redistribution of channels had only small effect on the conduction velocity whereas physical changes to myelin were primarily responsible for the effects,” Dr. Hamann said.
The research adds further strength to the link between myelin sheath deficit and hearing loss. This is the first time a simulation was used to assess the physical changes to the myelin coat based on previous morphological data. Armed with these findings, published in the journal Frontiers in Neuroanatomy, scientists have come to a better understanding of now only how auditory perception can become dull, but also what makes a good hearing. Translating into practice, the research suggests targeting these deficits; namely, promoting mylein repair after acoustic trauma or during age related loss.
A personal note: while summer's almost gone, there are still some festivals where you might be exposed to loud music. Also, there are always loud clubs, whether you like it or not, that are open no matter the season. The best protip I can offer is to wear earplugs. I can't stress this enough. These simple tools, highly effective and cheap, can protect you against the excess decibels monster speakers throw at you, all while preserving sound quality.