1. Hearing: How do we hear?

2. Our Essential Questions
What are the major parts of the ear?
How does the ear translate sound into neural impulses?

3. Sound
What part of the brain?
Sound comes in waves
Vibration

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
Measured as hertz (Hz)

6. Hertz (Hz)
Measure of the number of sound wave peaks per second; measures frequency
Determines the pitch of the sound
Human hearing: 20 Hz - 20,000 Hz

7. What pitch can you hear?

8. Decibel (dB) A measure of the height of the sound wave
Loudness of the sound
Amplitude

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

11. Hearing: The Structure of the Auditory System

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

13. Break It Down
Sound waves are collected in the outer ear, amplified in the middle ear, and transduced, in the inner ear.

14. The outer ear collects sound
Divisions of the Ear
The outer ear collects sound

15. Parts of the Outer Ear – Pinna
The visible part of the outer ear.
collects sound and directs it to auditory canal

16. Parts of the Ear – Sound Waves

17. Parts of the Outer Ear – Auditory Canal
The opening, tunnel that sound waves travel through
Ends at the eardrum
Parts of the Outer Ear – Auditory Canal

18. Parts of the Outer Ear – Auditory Canal

19. The middle ear amplifies sound
Divisions of the Ear
The middle ear amplifies sound

20. Parts of the Middle Ear - Eardrum
AKA tympanic membrane
Thin membrane that vibrates when sound waves reach it
Transfers sound vibration from the air to the tiny bones of the middle ear
Damage?

22. Parts of the Middle Ear – Tympanic Membrane

23. Parts of the Middle Ear - Ossicles
3 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

25. Parts of the Middle Ear - Occicles

26. The inner ear transduces sound
Divisions of the Ear
The inner ear transduces sound

27. Parts of the Inner Ear - Oval Window
Intersection of the middle ear with the inner ear
Touches the stirrup
As the oval window vibrates, the fluid in the cochlea vibrates
From eardrum  oval window, sound is amplified 20 times

28. Parts of the Inner Ear – Oval Window

29. Parts of the Inner Ear - 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

30. Parts of the Ear - Cochlea

32. Parts of the Inner Ear - Hair Cells
The receptor cells …what do they do?
Transduction!

33. Parts of the Inner Ear - Hair Cells

34. Parts of the Inner Ear - Auditory Nerve
carries sound information from the ears to the brain
Like the optic nerve

35. Parts of the Inner Ear – Auditory Nerve

36. Hearing - Review Sound is collected by pinna
Goes through the ear canal to the eardrum
Eardrum changes sound  vibrations
Vibrations go from middle ear  inner ear via oval window

37. Hearing - Review
Here vibrations  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. Problems with hearing
Cochlear Implants:

40. Hair Cell Loss
Read the article “How the iPod and other audio devices are destroying your ears”
Answer the review questions at the end

41. Localization of Sound Locating where sound is originating from
Done through two cues:
Which ear hears the sound first?
Which ear hears the sound louder?

42. Localization of Sound

43. YOU Break It Down This Time
Sound waves are ______ in the outer ear, _______ in the middle ear, and ________, in the inner ear.

44. Is there another sense in your ear?

45. Vestibular Sense
body orientation and balance
Receptor cells: semicircular canals, hair cells in inner ear
Parietal lobes
Motion sickness = overstimulation

46. Parts of the Ear – Semicircular Canals

47. Parts of the Ear – Semicircular Canals

48. Semicircular canal
What situations will affect the semicircular canal?

49. Let’s Process Get a 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
Together, briefly describe how sound is changed into neural impulses

50. UKULELE