|MadSci Network: Other|
Kelly, There are probably a couple of reasons why we don't usually hear our eyelashes batting. First, whatever sound our eyelids produce when we blink is very quiet. Our hearing system is extrmemely sensitive, but very quiet sounds are easily "masked" or "covered up" by other, louder, sounds in our environment. If you really pay attention I bet you will find that most rooms you are in actually have a good deal of noise even when they seem quiet. Listen carefully and you'll probably notice the rumble of a fan or a heater, noise from other parts of the building, maybe even voices from another room. Sounds like these can mask our ability to detect other very quiet sounds. If you were in a special sound-proof room that blocks all of these extra sounds, you might be able to hear your eyelids blink! However, even in a sound-proof room you might not hear your eyelashes batting because another process is at work. Our brains work in such a way that messages from the outside world that are constant and relatively unchanging are not as "noticeable" as those that change quickly. Think of touch for example. Most of the time you are probably quite unaware of the touch of your clothes on your body. They are constantly touching you, but you don't really perceive them. This is a form of what is called adaptation. When a message from the world is pretty constant, our brains seem to begin to "ignore" them after time! Adaptation occurs in hearing too. We must constantly blink our eyelids, so any sound created by batting your eyelashes may be hard to hear due to adaptation. If you have more questions, feel free to email me. Lori Holt firstname.lastname@example.org
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