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How do the stapes and oval window transmit vibrations into the cochlea?

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Watch a suspended vibrating spring to learn about the propagation of sound waves — sound Learn about the propagation of sound waves from a point source by observing the motion of a suspended vibrating spring.

The stapes and the oval window function as a critical interface for transmitting sound into the inner ear. Because sound waves must transition from air to the fluid-filled environment of the cochlea, the middle ear acts as an impedance-matching transformer to prevent significant energy loss.1

The stapes, the smallest of the three ear bones, has a footplate that fits precisely into the oval window, where it is secured by the annular ligament. The ossicular chain concentrates the sound energy collected by the eardrum membrane onto the much smaller area of the stapes footplate, significantly increasing the pressure applied to the cochlear fluids.21

As the stapes vibrates against the oval window, it creates pressure waves in the perilymph of the scala vestibuli. This mechanical action is made effective because the ossicular chain delivers sound selectively to the oval window, while the round window acts as a relief valve, moving in a reciprocal fashion to allow the fluid to displace and stimulate the basilar membrane.31