1. From Vibration to Sound
HEARING
From Vibration to Sound

2. Main Objective
Describe the auditory sensation that results when sound waves are collected in the outer ear, amplified in the middle ear, and converted to neural messages in the ear.

3. Key Questions
How do sound waves produce different auditory sensations?
What are the key structures of the ear and their functions?

4. Sound Sound, like light, comes in waves Sound is vibration
Features of sound include:
Pitch
Timbre
Decibels
Loudness
Frequency
Amplitude

5. Audition The sense of hearing.
Makes you capable of responding to a wide range of sounds, from faint to blaring, simple to complex, harmonious to discordant.

6. Loudness
The intensity (or amplitude) of a sound wave, measured in decibels.

7. Amplitude
The intensity or amount of energy of a wave, reflected in the height of the wave.

8. Healthy Amplitude (volume)?
What volume do you think is okay?
Not good, not bad?
Handout (slide 15)

9. Components of a Sound Wave

10. Decibels (dB)
The unit of measurement for loudness.

11. Pitch A sound’s highness or lowness
Dependent on the frequency of the sound wave
Is measured as hertz (Hz)

12. Frequency

13. Timbre (TAM-ber)
The distinctive quality of a sound, determined by the complexity of the sound wave.
Every human voice had a distinct, unique timbre.

14. Did you know that an
iPod at peak volume
Is 115 dB?

15. HEARING: How We Hear. The Path of Sound

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

17. Divisions of the Ear

18. The Outer Ear The part of the ear that collects sound waves.
Consists of the pinna, the ear canal, and the eardrum.

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

20. Parts of the Ear – Auditory Canal

21. 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?

22. Localization of Sound

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

24. 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

26. The Middle Ear The part of the ear that amplifies the sound waves.
Consists of three small bones, the hammer, the anvil (incus), and the stirrup (stapes).

27. 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

28. THE MIDDLE EAR

29. The Inner Ear
The part of the ear where sound is transduced into neural impulses.
Consists of the cochlea and the semicircular canals.

30. Cochlea A fluid filled tube that is coiled in a spiral.
Greek for snail.
Complex structure that is smaller than a pea.

31. Semicircular Canals
Organs in the inner ear used in sensing body orientation and balance (vestibular sense)
Relies on fluid in the canals
Spinning in circles disrupts the fluid.

32. Oval Window
The point on the surface of the cochlea which receives the sound vibration from the ossicles
As the oval window vibrates, the fluid in the cochlea vibrates.

33. Parts of the Ear – Oval Window

34. Basilar Membrane
The membrane within the cochlea of the ear that contains the hair cells.

35. Hair Cells
The hairlike sensory receptors for sound, which are embedded in the basilar membrane in the cochlea.

36. Parts of the Ear - Hair Cells

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

38. Divisions of the Ear Review ~ What is included in each section?
The outer ear
The middle ear
The inner ear

39. 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.

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

41. Quiz Time!