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Or at least a mouse's brain. Interesting study on how prolonged exposure to high SPLs physically alters the auditory nerves. Synaptic nerve endings are enlarged, while production of neurotransmitters is reduced, possibly allowing the mouse to block out the irrelevant noise and focus on more meaningful, lower SPL sounds occurring at the same time. The alteration is non-permanent: reduce noise exposure for awhile, and the cells go back to normal. Thanks to Mike S on the PE forum for the link.
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This is not news.
We have known for many decades that we, and other critters, "zero in" on sounds which "matter".
Another waste of taxpayer dollars to re-research that which is already known.
:)
There is a big difference between suspecting, or "knowing" something to be the case and actually showing it empirically. It is nice to see a synaptic level change like this as opposed to some vague (i.e., "zero in") understanding at the phenomenological level.
. . . is the documentation of actual noise-induced physical changes to the neurons of the auditory nerve. This may in fact have implications down the road for the medical treatment of hearing loss.
I'm a taxpayer, and don't consider this sort of research a "waste" of my dollars. I'd certainly rather my money went toward scientific research than toward blowing up third-world peasants and earning my country still more enemies.
Thanks! for sharing. There is plenty of money for both research and exterminating the cocka roaches.
Well, I guess y'all told me a thing or two.Still, I'm reminded of a sound isolation situation from about 10 years ago,when I told the piano teacher that it would be harder to isolate the piano from the other rooms than if it were random noise. I explained to her that this is one reason why birdsong "carries" so well over long distances, and can be easily heard even with high levels of environmental "noise".
:)
Edits: 06/09/15
My understand is that prolonged loud noise does irreversible damage.
Percussive / impulsive sound is particularly harmful. This is because our hearing mechanism doesn't have time to respond to it, and so passes the sound unhindered to the cochlea. The muscles in the middle ear normally contract/stiffen when presented with a loud sound, to protect the inner ear from damage. With percussive sounds, they can't react fast enough.Examples of such sounds include drums, gunshots, drop forges, and other sounds which have a very short rise time to their loud peak level.
You (the collective 'you') may have heard the term "temporary threshold shift". This happens when the muscles tighten in response to loud sounds, such as when a person goes to a loud nightclub or concert. After a while, they relax, and your hearing returns to normal. Unfortunately, repeated exposure to sound causes the muscles to lose their ability to protect the inner ear, resulting in damage to the hairs in the cochlea, which results in hearing loss.
There is a very good explanation of this in Anita Lawrence's "Architectural Acoustics", as well as in "Why You Hear What You Hear" by Dr. Eric Heller, and in numerous papers in the journal of the ASA.
:)
Edits: 06/11/15
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