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Hearing: How do we hear?

Hearing: How do we hear?. Hearing: The Nature of Sound. Module 9: Sensation. Sound. Sound, like light, comes in waves Sound is vibration Features of sound include: Pitch Hertz decibels. Pitch. A sound’s highness or lowness

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Hearing: How do we hear?

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  1. Hearing: How do we hear?

  2. Hearing: The Nature of Sound Module 9: Sensation

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

  4. Pitch • A sound’s highness or lowness • Dependent on the frequency of the sound wave – the more “waves per second” the higher the frequency or pitch • Is measured as hertz (Hz)

  5. Hertz (Hz) • A measure of the number of sound wave peaks per second; measures “frequency” • Determines the pitch of the sound • One Hertz = one vibration per second

  6. Low Pitch • Wave peaks are far apart Human hearing goes from 20 Hz to 20,000 Hz although some ears (and speakers) are better than others

  7. High Pitch • As pitch increases, so do the number of waves Remember - Human hearing goes from 20 Hz to 20,000 Hz note: a kilohertz is 1,000 hertz so 20 kilohertz equals 20,000 hertz

  8. Decibel (dB) • A measure of the height of the sound wave • Determines the loudness of the sound • Sometimes called amplitude

  9. What are good sounds versus bad • What volume do you think is okay? • Not good, not bad? • Bad?

  10. Hearing: The Structure of the Auditory System Module 9: Sensation

  11. Break It Down • Sound waves are collectedin the outer ear, amplifiedin the middle ear, and transduced, in the inner ear.

  12. PINNA The visible part of the outer ear. • It collects sound and directs it into the outer ear canal.

  13. Parts of the Ear – Sound Waves

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

  15. Parts of the Ear – Auditory Canal

  16. THE MIDDLE EAR

  17. Eardrum • Also called the tympanicmembrane. 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

  18. Parts of the Ear – Tympanic Membrane

  19. 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

  20. Parts of the Ear - Occicles

  21. 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.

  22. Parts of the Ear – Oval Window

  23. 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

  24. Parts of the Ear - Cochlea

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

  26. Parts of the Ear - Hair Cells

  27. Parts of the Ear – Oval Window

  28. Auditory Nerve • The nerve that carries sound information from the ears to the temporal lobes of the brain

  29. Parts of the Ear – Auditory Nerve

  30. Divisions of the Ear • Ear’s structure can be divided into: • The outer ear • The middle ear • The inner ear

  31. Divisions of the Ear

  32. Divisions of the Ear

  33. Divisions of the Ear

  34. REVIEW Hammer • The Ossicles amplify the vibration of the eardrum Anvil Stirrup Ear Drum

  35. Movement of the fluid causes the hair cells to move which causes TRANSDUCTION!

  36. REVIEW • 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 –

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

  38. Problems with hearing • Conduction deafness* (middle ear damage) • Nerve deafness (hair cell or auditory nerve damage)

  39. Hearing: Sound Localization Module 9: Sensation

  40. 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?

  41. Localization of Sound

  42. Another sense in your ears? • Is there another sense in your ear?

  43. 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.

  44. Parts of the Ear – Semicircular Canals

  45. Parts of the Ear – Semicircular Canals

  46. Semicircular canal • What situations will affect the semicircular canal

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