As sound waves enter the ear, they travel through the outer ear, the external auditory canal, and strike the eardrum causing it to vibrate.
The central part of the eardrum is connected to a small bone of the middle ear called the malleus (hammer). As the malleus vibrates, it transmits the sound vibrations to the other two small bones or ossicles of the middle ear, the incus and stapes.
As the stapes moves, it pushes a structure called the oval window in and out. This action is passed onto the cochlea, which is a fluid-filled snail-like structure that contains the receptor organ for hearing.
The cochlea contains the spiral organ of Corti, which is the receptor organ for hearing. It consists of tiny hair cells that translate the fluid vibration of sounds from its surrounding ducts into electrical impulses that are carried to the brain by sensory nerves.
As the stapes rocks back and forth against the oval window, it transmits pressure waves of sound through the fluid of the cochlea, sending the organ of Corti in the cochlear duct into motion. The fibers near the cochlear apex resonate to lower frequency sound while fibers near the oval window respond to higher frequency sound.
Review Date: 10/5/2008
Reviewed By: Luc Jasmin, MD, PhD, Gene Therapeutics Research Institute, Cedars-Sinai Medical Center, Los Angeles CA. Review provided by VeriMed Healthcare Network.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2009 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.