Unit 5 Hearing

Question 1

Define sound

Answer 1

Sound is the compression and rarefaction of air molecules. Sound waves have an amplitude and a frequency

Question 2

Identify the various parts of the outer ear

Answer 2

The pinna and the tympanic membrane

Question 3

Describe sensory transduction for sound

Answer 3

1) The vibrating fluid inside the cochlea lifts the basilar membrane

2) This pushes the stereocilia (little hairs) of the inner hair cells against the tectorial membrane.

3) the stereocilia on the inner hair cells are displaced (bent), which increases the distance between the stereocilia increases. this tugs on little proteins chains (called tip links) opening the cation channels

4) Once the cation channels have opened, cations flow in and depolarize the inner hair cells. This causes voltage-gated Ca2+ channels to open triggering neurotransmitter release. These neurotransmitters activate the neurons of the vestibulochlear nerve, sending action potentials back to the brain.

5) The axons of the (bipolar) spiral ganglion neurons carry sound information back to the brain as part of the vestibulocochlear nerve.

Question 4

what role does the basilar membrane play?

Answer 4

It supports hair cells, serves as the base layer of the organ of Corti, and propagates sound vibrations that allow the brain to interpret sound

Question 5

what are the roles of the outer, middle, and inner ear?

Answer 5

The outer ear captures, focuses, and filters sound

The inner ear uses vibrations to transmit sound waves to the inner ear

The inner ear transforms sound waves into electrical impulses

Question 6

Describe the journey of the sound information through the brain

Answer 6

auditory nerve runs from your cochlea to a station in your brain stem. From that station, neural impulses travel to your temporal lobe where your brain attaches sound to meaning.

Question 7

Describe the meaning of tonotopic organization

Answer 7

refers to the idea that auditory regions in the brain are organized based on the frequency of sound they respond to.

Question 8

Describe the term pitch and briefly discuss the two theories regarding our ability to discriminate pitch.

Answer 8

Pitch refers to the frequency. Place coding is the frequency of sound is coded based on the location along the basilar membrane that responded to that sound.
Temporal coding is the frequency of sound is represented in the frequency of the resulting neural impulses.

Question 9

Discuss how we localize sounds

Answer 9

We localize sound by using input from both ears. This is called Interaural intensity differences and Interaural temporal differences

Question 10

Describe the three main causes of deafness and the function of cochlear implants.

Answer 10

Conduction deafness: outer ear or middle ear does not conduct sound.

Sensorineural deafness: This is the most common form of deafness. It usually results from damage to the hair cells

Central deafness: damage to brain regions

Cochlear implants can be used in cases of sensorineural hearing loss as a means to convert some information about sound into neural impulses that will be sent to the brain

Question 11

Define amusia and discuss a possible cause.

Answer 11

Amusia means the axons connecting the temporal and frontal lobe are diminished.

The causes are from birth or from an injury

Question 12

Identify the parts of the middle ear

Answer 12

Ossicles: malleus, incus, stapes

Question 13

Identify the parts of the inner ear

Answer 13

Round window, oval window, cochlea, organ of corti