CMD 278 Lecture Notes - Lecture 2: Ear Canal, Oval Window, Basilar Membrane
22 Sep 2016
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Document Summary
Vibration of air molecules in air leads to vibration of air molecules in the external auditory canal: sound is traveling in the medium of air. Perilymph in scala vestibule moves in a wave-like motion: medium has now changed to liquid. Leads to a loss of sound intensity as sound moves from a low impedance medium (air) to a higher impedance medium (liquid: about 35 ddbspl of sound is lost in transition. The unique properties of the ossicular chain offset this intensity loss: mechanical advantage of the middle ear. Ossicles act as a lever, get back about 2 db. On average 17:1, get back about 25 db. Perilymph can move between scala vestibule and scala tympani via the helicotrema. When the bm moves, the organ of corti moves as well. The ap is the firing of the neurons in the organ of corti. First described by georg von bekesy in the 1930"s-40"s.
