A comment on last Wednesday’s article correctly reminded us that there seems to be some confusion about the phenomenon known as auditory exclusion.
Under times of high stress, such as a violent criminal attack, the body makes profound physiological adjustments to limit distracting data and focus on the threat. One of these is to radically attenuate (or even completely silence) aural inputs – in other words, it shuts your hearing down. This is called auditory exclusion.
It’s important to understand that auditory exclusion is performed in the brain, not in the ears themselves. Though your brain isn’t accepting the audio data being collected, your ears are still collecting it. It’s a filtering mechanism, where the brain decides what’s unimportant and ignores that to concentrate on what is important.
Since the physical parts of the ears are still functioning, they can and will be damaged by high sound levels just as they would under high sound pressure levels in a non-stressful environment. The tympanic membrane and the fragile hairs of the cochlea can still be profoundly affected by gunfire even in a high stress environment.
No doubt someone reading this is thinking “what about the aural reflex mechanism, smart guy?” Aural reflexes do physically protect your hearing by changing the curvature of the eardrum, and preventing the tiny bones of the inner ear from transmitting vibrations to the cochlea. This is designed to protect the sensitive parts of the ear from sustained loud sound. The key here is the word “sustained”; gunshots are simply too short in duration to activate the aural reflexes, and are not a function of auditory exclusion.
Simply put, auditory exclusion just doesn’t pull a blanket over your ears to protect them!
In the case of a shooting, the extreme noise levels are doing damage to your ears even though your mind isn’t reporting anything. It isn’t until the aftermath, when your body starts to return to normal, that your brain turns the audio back on. That’s when you discover that you don’t hear as well as you used to.
The rationalization that “during a fight, you won’t hear those Magnum rounds going off” is true, but the implication that auditory exclusion is preventing all harm to your ears isn’t. You’re going to have to weigh the risk of a certain amount of hearing loss, however small, against the perceived effectiveness of the ammunition being considered.
-=[ Grant ]=-
- Posted by Grant Cunningham
- On August 24, 2009