Tuesday, April 16, 2013

Amplifier

Scientists have understood for some time how the ear turns sound vibrations into electrical impulses that the brain interprets.

The keys are tiny cells inside the ear called "hair cells," which look like what their name implies. As they move, they create those elctrical impulses. The louder the sound, the more hair cells move and the more energy is used. Exactly how the hair cells manage their role is not as well understood. They're hard to see when they're in place inside the ear and when they're not in place or when they're being observed in a cadaver, they don't function. Plus, the hair cells in human and other mammal's ears are delicate enough that it's pretty tough to remove them from their enviroment without damaging them. This delicacy is one reason why prolonged exposure to loud noises causes hearing loss. The hair cells more or less burn out like a lightbulb.

But the hair cells in frogs are tough and quite a bit easier to see, and by studying them, scientists have learned some things. For one, the cells themselves seem to have random patterns of movement and don't just sit still. Since scientists were studying frogs, they were not able to ask if this movement meant the frogs were "hearing things" even when there was no sound, since frogs don't talk (although there are uncomfirmed reports that at least one has an excellent singing voice). Attempts to reach one Mr. Toad of Toad Hall for comment were unsuccessful.

When stimulated by sound, the random movement synchronizes with the hair cells that are being affected by the noise and may amplify the signal to the brain -- a kind of cellular auditory peer pressure. When sounds are very soft, the synchronization isn't as exact and sometimes it's lost. All sorts of acoustic conditions can affect which sounds the ear picks up and what signals it transmits.

Unfortunately, scientists do not at this point have any information on ways to turn one's hair cells off when politicians or Donald Trump are speaking, which means we usually have to leave the area when they start talking.

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