Audition

Question 1

Components of the outer ear

Answer 1

Pinna, auditory canal

Question 2

Components of the middle ear

Answer 2

Tympanic membrane (ear drum), ossicles

Question 3

Components of the inner ear

Answer 3

Cochlea (with hair cells)

Question 4

What is sound caused by?

Answer 4

Small areas of high and low pressure propagating outward from the source

Question 5

How does the tympanic membrane respond to sound?

Answer 5

It vibrates! High pressure pushes it inward, low pressure pulls it outward

Question 6

How are vibrations transmitted from the ossicles to the cochlea?

Answer 6

Through the oval window (membrane on the cochlea that ossicles are attached to)

Question 7

What is the purpose of hair cells?

Answer 7

To convert mechanical energy of vibrations to electrical energy to send to the brain for processing

Question 8

What do hair cells synapse on?

Answer 8

Spiral ganglion cells

Question 9

Facts about spiral ganglion cells

Answer 9

Each is tuned to a specific frequency - represents a bell curve with the preferred frequency in the middle

Question 10

What is tinnitus and what 3 things can potentially cause it?

Answer 10

It’s when a person hears noises in the absence of any auditory stimulus.
It’s caused by either exposure to loud music (for transient/temporary tinnitus), disease processes affecting cochlea/auditory nerve, or spontaneous activity (bonus: from OHC!)

Question 11

Track the sound waves from the environment to the brain stem

Answer 11

Pinna traps sound, focuses in auditory canal.
Sound vibrates ear drum, ossicles, and oval window.
Vibrations move through fluid in cochlea and moves hair cells, which convert the movement into an electrical signal. Electrical signal is transmitted to spiral ganglion cells, which join vestibulocochlear nerve (auditory nerve), which synapse on cells in brain stem.

Question 12

Which two senses does the inner ear take care of?

Answer 12

Sense of hearing and sense of balance (vestibular system)

Question 13

Which nerve carries both auditory and balance information to the brain?

Answer 13

Vestibulocochlear nerve

Question 14

Track electrical signals from the brain stem to the primary auditory cortex

Answer 14

Information passed from vestibulocochlear nerve to cochlear nuclei (in the lower pons/upper medulla) and then bilaterally sent to inferior colliculi.
Inferior colliculi send information to medial geniculate nucleus (MGN) in the thalamus.
MGN sends information to primary auditory cortex (in superior temporal lobe).

Question 15

Where is the thalamus?

Answer 15

It is the two bumps on the midbrain and has a lot of nuclei/purposes

Question 16

What is the first region of the cortex to actually process sound?

Answer 16

Primary auditory cortex

Question 17

How are the cells arranged in both the cochlea and primary auditory cortex?

Answer 17

In a tonotopic map

Question 18

Where is the primary auditory cortex located?

Answer 18

In the superior temporal lobe, buried in the lateral sulcus

Question 19

Method for sound localisation on the horizontal axis

Answer 19

Interaural time: differences between the arrival time of sound at each ear

Question 20

Method for sound localisation on the vertical axis

Answer 20

Depends on reflections of sound bouncing off the pinnae

Question 21

Does all auditory information cross the midline?

Answer 21

Nope! Each ear projects info to both hemispheres. This means that damage to one side isn’t catastrophic

Question 22

What do cochlear implants do?

Answer 22

Stimulate functioning spiral ganglion cells, bypassing the hair cells

Question 23

What are some limitations of cochlear implants?

Answer 23

Replaces 16,000 hair cells with usually 24 electrodes, does not restore normal hearing but replaces it with something else