Mia Tazi

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24-6 How We Hear

• Mia Tazi
• Emily Partridge
• Ohee Jeon
• Grayson Dawson

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Presentation Outline

• The Ear Has Three Parts
• Outer Ear
• Middle Ear
• Inner Ear
• Key Elements For Hearing
• How The Ear Functions

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Sound

• Sound is a form of energy that causes particles
  of a medium to vibrate back and forth

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3 Things Needed For Sound To Be Heard

• A source that produces the sound.
• A medium to transmit the sound.
• An organ of the body that detects the sound. In
  humans, the organ of the body that detects sound
  is the ear.

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Outer Ear

• The outer ear acts as a funnel for the sound
  waves.
• The waves move through the ear canal and strike a
  lightly stretched membrane called the eardrum.
  This causes the eardrum to vibrate.
• The vibrations enter the middle ear.

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Middle Ear

• The middle ear contains the three smallest bones
  in the body.
• The hammer, picks up vibrations from the eardrum
  and passes them to the anvil.
• The anvil transmits the vibrations to the
  stirrup.
• The stirrup sets another membrane vibrating. This
  membrane transmits the vibrations to the inner
  ear.

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Inner Ear and the Cochlea

• The vibrations in the inner ear are channeled
  into the cochlea.
• The cochlea contains a liquid and hundreds of
  cells attached to nerve fibers.
• These fibers join together to form one nerve that
  goes to the brain.

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Steps to Hearing

• Sound waves enter the outer ear.
• Waves move through the ear canal and strike the
  eardrum, causing the eardrum to vibrate.
• Vibrations from the eardrum enter the middle ear.
• Hammer picks up the vibration and passes them to
  the anvil. The anvil transmits the vibrations to
  the stirrup, which sets another membrane
  vibrating.

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Steps to Hearing

• The vibrations are transmitted into the inner
  ear, and then to the cochlea, which contains
  hundreds of cells attached to nerve fibers.
• The cells detect movement in the liquid of the
  cochlea and convert them into electrical
  impulses.
• The nerve fibers transmit the impulses to the
  brain, where they are then interpreted as sound.

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The Human Ear
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Definitions

• Outer Ear - part of the ear that funnels sound
  waves into the ear.
• Eardrum - stretched membrane in the ear that
  vibrates at the same frequency as the sound waves
  that enter the ear.
• Middle Ear - part of the ear that receives
  vibrations from the eardrum and contains the
  hammer, anvil, and stirrup.
• Inner Ear - liquid filled portion of the ear that
  receives vibrations from the middle ear.
• Cochlea - part of the ear that contains hundreds
  of nerve cells attached to nerve fibers.

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You Have Just Learned

• Descriptions of the Ear
• Outer Ear
• Middle Ear
• Inner Ear
• Key Elements for Hearing
• How the Ear Functions