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Understanding Auditory Transduction Processes

Aug 6, 2024

Sense of Hearing and Auditory Transduction

Key Concepts

  • Auditory Transduction: The process by which the ear converts sound waves into electrical impulses for the brain to interpret as sound.

Pathway of Sound

  1. Sound Entry

    • Sound enters through the external auditory canal.
    • Sound waves meet and vibrate the tympanic membrane.

  2. Tympanic Membrane

    • Vibrates in response to sound waves.
    • Lower frequency (pitch) sounds: Slower vibration rate.
    • Lower amplitude (volume) sounds: Less dramatic vibration.
    • Higher frequency sounds: Faster vibrations.
    • Cone-shaped structure.

  3. Auditory Ossicles

    • Chain of three bones: Malleus, Incus, Stapes.
    • Vibrations from the tympanic membrane pass to the ossicles.

  4. Bony Labyrinth

    • Stapes moves in a piston-like action, sending vibrations into the bony labyrinth.
    • Labyrinth filled with fluid called perilymph.
    • Round window membrane: Allows stapes' movement to displace perilymph.

  5. Cochlea

    • Spiral portion of the bony labyrinth.
    • Vibrations ascend through the scala vestibuli and descend via the scala tympani.
    • Cochlear duct situated between the scala vestibuli and scala tympani.
    • Cochlear duct filled with endolymph.

  6. Membranes

    • Reissner's membrane: Separates scala vestibuli and cochlear duct.
    • Basilar membrane: Separates cochlear duct and scala tympani, supports organ of Corti.

  7. Organ of Corti

    • Located on the basilar membrane.
    • Vibrations stimulate the organ of Corti, generating nerve impulses.

  8. Hair Cells and Tectorial Membrane

    • Hair cells in the organ of Corti are covered by the tectorial membrane.
    • Vibrations bend hair clusters against the tectorial membrane, triggering nerve impulses.

Tonotopic Organization

  • Specific regions of the basilar membrane vibrate in response to different sound frequencies.
    • Lower frequencies: Vibrate near the apex of the cochlea.
    • Higher frequencies: Vibrate near the base of the cochlea.

Summary

This sequence of events, from the entry of sound waves into the ear to the generation of nerve impulses by the hair cells, constitutes our acoustic perception of the world.

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