Editing Ossicles (section)

== Function ==
{{Unreferenced section|date=December 2024}}
As sound waves vibrate the tympanic membrane (eardrum), it in turn moves the nearest ossicle, the malleus, to which it is attached. The malleus then transmits the vibrations, via the incus, to the stapes, and so ultimately to the membrane of the fenestra ovalis (oval window), the opening to the vestibule of the inner ear.

Sound traveling through the air is mostly reflected when it comes into contact with a liquid medium; only about 1/30 of the sound energy moving through the air would be transferred into the liquid.<ref>Hill, R.W., Wyse, G.A. & Anderson, M. (2008). ''Animal Physiology, 2nd ed..''</ref> This is observed from the abrupt cessation of sound that occurs when the head is submerged underwater. This is because the relative incompressibility of a liquid presents resistance to the force of the sound waves traveling through the air. The ossicles give the eardrum a [[mechanical advantage]] via lever action and a reduction in the area of force distribution; the resulting vibrations are stronger but don't move as far. This allows more efficient coupling than if the sound waves were transmitted directly from the outer ear to the oval window. This reduction in the area of force application allows a large enough increase in [[pressure]] to transfer most of the sound energy into the liquid. The increased pressure will compress the fluid found in the cochlea and transmit the stimulus. Thus, the lever action of the ossicles changes the vibrations so as to improve the transfer and reception of sound, and is a form of [[impedance matching]].

However, the extent of the movements of the ossicles is controlled (and constricted) by two muscles attached to them (the ''[[tensor tympani]]'' and the ''[[stapedius]]''). It is believed that these muscles can contract to dampen the vibration of the ossicles, in order to protect the inner ear from excessively loud noise (theory 1) and that they give better frequency resolution at higher frequencies by reducing the transmission of low frequencies (theory 2) (see [[acoustic reflex]]). These muscles are more highly developed in [[bat]]s and serve to block outgoing cries of the bats during [[Animal echolocation|echolocation]] (SONAR).