The Ossicles

The three tiniest bones in the body form the coupling between the vibration of the eardrum and the forces exerted on the oval window of the inner ear.

With a long enough lever, you can lift a big rock with a small applied force on the other end of the lever. The amplification of force can be changed by shifting the pivot point.

The ossicles can be thought of as a compound lever which achieves a multiplication of force. This lever action is thought to achieve an amplification by a factor of about three under optimum conditions, but can be adjusted by muscle action to actually attenuate the sound signal for protection against loud sounds.

A physiology book describes the ossicles as the smallest bones int he body, small enough to fit collectively on a U.S. dime.

Sketch of ossicle vibraton
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Ossicle Vibration

The vibration of the eardrum is transmitted to the oval window of the inner ear by means of the ossicles, which achieve an amplification by lever action. The lever is adjustable under muscle action and may actually attenuate loud sounds for protection of the ear.

Index

Hearing concepts
 
HyperPhysics***** Sound R Nave
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