Auditory Transduction and the Doppler Effect - Notes

Auditory Transduction

  • Auditory transduction is the process where the ear converts sound waves into electrical impulses.
  • These impulses are then sent to the brain for interpretation as sound.

The Process of Auditory Transduction

  • It begins with a sound wave entering the ear canal.
  • The sound wave causes the eardrum (tympanic membrane) to vibrate.

Role of the Eardrum

  • The vibrating eardrum is connected to the malleus (hammer).
  • This causes the malleus to vibrate.

Auditory Ossicles

  • The malleus moves the incus (anvil).
  • The incus moves the stapes (stirrup).
  • These three bones (malleus, incus, and stapes) are the smallest bones in the human body and are called the auditory ossicles.

Stapes and Cochlea

  • The base of the stapes is connected to the cochlea.
  • When the stapes vibrates, it creates waves in the fluid (perilymph) within the cochlea corridors.

Cochlea Corridors

  • The stapes sends waves up the scala vestibuli.
  • The waves then travel down the scala tympani.

Electrical Impulse Creation

  • The electrical impulse is created in the basilar membrane.
  • The basilar membrane is located between the scala vestibuli and scala tympani (the up and down corridors).

Cochlear Implant

  • A cochlear implant bypasses the normal workings of the ear.
  • It sends electrical signals directly to the auditory nerve.
  • These signals are not the exact signals typically used for sound.
  • The brain learns to interpret these signals and figures out how to use them.

The Doppler Effect

  • The Doppler effect is a change in the perceived pitch of a sound due to relative motion between the sound source and the receiver.

Approaching Sound Source and Receiver

  • If the sound source and receiver are moving toward each other:
    • The frequency of the sound will be greater than if they were not moving toward each other.

Receding Sound Source and Receiver

  • If the sound source and receiver are moving away from each other:
    • The frequency of the sound will be less than if they were not moving away from each other.