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Rikiki (![[info]](http://www.journalfen.net/img/userinfo.gif){kind=small} rikiki) wrote,@ 2008-09-02 09:45:00 |
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THEA283 Notes 02 Sep 08 - The Human Ear - a quick lesson in how we hear
- The Human Ear - three main parts
- Outer Ear
- external auditory canal
- Middle Ear
- Inner Ear
- provides balance
- How does it work?
- Airborne vibrations are collected in the external ear and have to be conveyed to the fluid of the inner ear without losing energy
- Accomplished by the middle ear which matches the acoustic properties of air to the more dense fluid of the inner ear
- Next, vibrations must have access to sensory cells of inner ear which are bathed in fluid, which is encased in bone, and potentially incompressible
- there has to be one opening in the inner ear for vibrations to enter and another to act as release valve
- base of the stapes rocks in and out against the oval window - entrance for vibrations
- vibrations go from scala vestibuli to scala media to scala tympani to round window (release valve)
- different frequencies cause different movements of basilar membrane (floor of the scala media)
- greater the displacement, greater the stimulation
- In less medical terms
- Sound pressure waves collected by outer ear, converted to mechanical energy in the inner ear, reverted to pressure by inner ear, turned into impulses interpreted by brain
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