Hearing:%20How%20do%20we%20hear?

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Hearing How do we hear?
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Hearing The Nature of Sound

• Module 9 Sensation

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Sound

• Sound, like light, comes in waves
• Sound is vibration
• Features of sound include
• Pitch
• Hertz
• decibels

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Pitch

• A sounds highness or lowness
• Dependent on the frequency of the sound wave
• Is measured as hertz (Hz)

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Hertz (Hz)

• A measure of the number of sound wave peaks per
  second measures frequency
• Determines the pitch of the sound
• Human hearing goes from 20 Hz to 20,000 Hz

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Decibel (dB)

• A measure of the height of the sound wave
• Determines the loudness of the sound
• Sometimes called amplitude

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Pitch

• A sounds highness or lowness in tone
• Dependent on the frequency of the sound wave
  the more waves per second the higher the
  frequency or pitch
• Is measured as hertz (Hz)

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Hertz (Hz)

• A measure of the number of sound wave peaks per
  second measures frequency
• Determines the pitch of the sound
• Human hearing goes from 20 Hz to 20,000 Hz

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Decibel (dB)

• A measure of the height of the sound wave
• Determines the loudness of the sound
• Sometimes called amplitude

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What are good sounds versus bad

• What volume do you think is okay?
• Not good, not bad?
• Bad?

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Hearing The Structure of the Auditory System

• Module 9 Sensation

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Break It Down

• Sound waves are collected in the outer ear,
  amplified in the middle ear, and transduced, in
  the inner ear.

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PINNA
The visible part of the outer ear.

• It collects sound and directs it into the outer
  ear canal.

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Parts of the Ear Sound Waves
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Auditory Canal

• The opening through which sound waves travel as
  they move into the ear for processing
• Ends at the eardrum

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Parts of the Ear Auditory Canal
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THE MIDDLE EAR
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Eardrum

• Also called the tympanic membrane. A thin
  membrane that vibrates when sound waves reach it.
• it transfers sound vibration from the air to the
  tiny bones of the middle ear
• Can be damaged by objects in the ear or
  exceptionally loud noises

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Parts of the Ear Tympanic Membrane
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Bones of the middle ear - Ossicles

• Three tiny bones that transfer sound waves from
  the eardrum to the cochlea
• Hammer, anvil and stirrup
• Fun fact the stirrup is the smallest bone in the
  human body only .25 cm

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Parts of the Ear - Occicles
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Oval Window

• The point on the surface of the cochlea which
  receives the sound vibration from the bones of
  the middle ear (ossicles)
• As the oval window vibrates, the fluid in the
  cochlea vibrates.

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Parts of the Ear Oval Window
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Cochlea

• A hearing organ where sound waves are changed
  into neural impulses (transduction)
• The major organ of hearing
• Filled with fluid a snail shaped body tube

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Parts of the Ear - Cochlea
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Hair Cells

• The receptor cells for hearing in the cochlea
  that change sound vibrations into neural impulses
• Transduction!

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Parts of the Ear - Hair Cells
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Parts of the Ear Oval Window
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Auditory Nerve

• The nerve that carries sound information from the
  ears to the temporal lobes of the brain

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Parts of the Ear Auditory Nerve
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Divisions of the Ear

• Ears structure can be divided into
• The outer ear
• The middle ear
• The inner ear

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Divisions of the Ear
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Divisions of the Ear
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Divisions of the Ear
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Hearing

• Sound comes into the ear
• Goes through the ear canal to the eardrum
• Ear drum changes sound into vibrations
• Vibrations go through middle ear to the inner ear
  

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Hearing

• Where vibrations are changed into neural impulses
  so that the brain can read / interpret the sound
  
• What are the receptors cells for hearing?

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Problems with hearing

• Conduction deafness (middle ear damage)
• Nerve deafness (hair cell or auditory nerve
  damage)

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Hearing Sound Localization

• Module 9 Sensation

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Localization of Sound

• Locating where sound is originating from
• Done through two cues
• Which ear hears the sound first?
• Which ear hears the louder sound?

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Localization of Sound
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YOU Break It Down This Time.

• Sound waves are ______ in the outer ear, _______
  in the middle ear, and ________, in the inner ear.

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Another sense in your ears?

• Is there another sense in your ear?
• Time to do an experiment lets find out out to
  the hallway we go!!!!

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Vestibular Sense

• The system for sensing body orientation and
  balance
• Relies on fluid in the semicircular canals of the
  inner ear
• Spinning in circles disrupts the fluid.

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Parts of the Ear Semicircular Canals
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Parts of the Ear Semicircular Canals
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Semicircular canal

• What situations will affect the semicircular canal

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Lets Process

• Get a scrap piece of paper
• Trace the ear
• Label as much as you can by your self 60
  seconds
• Get with a partner fill in the rest