Sound (Audition)

Question 1

What is audition?

Answer 1

sense of sound

Question 2

What is needed for audition to occur?

Answer 2

1) Stimuli = pressurized sound wave

2) Receptor = hair cell located in the cochlea

Question 3

what is pressurized sound wave and what does it create?

Answer 3

1) when air molecules becomes pressurized (when there is less space so the molecules compress, which creates a high pressure)
2) air molecules try to escape, creating areas of high and low pressure (known as sound waves)

Question 4

Describe soundwaves.

Answer 4

1) can be close or far apart

2) have wavelengths (how high the peaks are)

Question 5

Smaller wavelength equals ________.

Answer 5

Greater frequency

Question 6

Large wavelengths equals __________.

Answer 6

smaller frequency (travels farther and penetrates deep into cochlea)

Question 7

What is the purpose of the cochlea?

Answer 7

1) allows you to listen to different soundwaves at the same time (ear breaks them up)
2) able to do this because sound waves travel different lengths along the cochlea.

Question 8

What happens when soundwaves travels through the ears?

Answer 8

1) Hit the pinna (outa ear)
2) Funneled from the pinna into the auditory canal (or external auditory meatus)
3) Sounds then hits the tympanic membane (ear drum)
4) TM begans to vibrate
5) Causes malleus, incus, and stapes (3 tiny bones) to vibrate - respectively in that order) — these bones are also referred to as the ossicles
6) Stapes is attached to elliptical window – causes this window to vibrate
6) Elliptical window is attached to cochlea (which has a bunch of fluid)
7) As the elliptical window is pushed inside and outside cochlea by the stapes - this causes fluid to be pushed in the cochlea
8) once fluid hits the tip of the cochlea, it goes backwards back to the elliptical window
9) Now, instead of going back into the elliptical window, the fluid goes into the circular window (causes circular window to get pushes out)
10) hair cells (cilia) move back and forth in the cochlea
11) This causes auditory nerve to send and electrical impulse to the brain

Keeps happening until the energy of the soundwave is dissipated and the fluid stops moving.

Question 9

What prevents fluid from going in the elliptical window?

Answer 9

Organ of corti (basilar and tectorial membranes) - runs inside of cochlea

Question 10

Outer ear

Answer 10

pinna to TM

Question 11

Middle Ear

Answer 11

Malleus to Stapes

Question 12

Inner Ear

Answer 12

semi-circle canals and cochlea

Question 13

Describe the organ of corti.

Answer 13

1) splits cochlea into 2 - upper and lower membrane

2) Has hair cells that move back and forth as the membranes are pushes up and down

Question 14

Describe the hair cells in the corti.

Answer 14

1) Has two parts: actual cell and hair bundle
2) Hair bundle and made of a bunch of filaments, each called kinocilium
3) Kinocilium are attached by “tip links”
4) Tip links (a spring like structure) are not directly attached to the kinocilium, but are attached to potassium channels

Question 15

What happens to the tip links when the kinocilium move back and forth

Answer 15

1) they get stretch and open up the potassium gated channels
2) K+ begins to flow into the cell
3) Causes Ca+ channels on the cell to open up (Ca+ flows into cell)
4) K+ and Ca+ flow into the cell, stimulating and action potential
5) AP Stimulates a spiral ganglion cell, which activates the auditory nerve, which sends the impulse to the brain

Question 16

The brain relies on the cochlea to do what?

Answer 16

Distinguishing sounds of varying frequencies. (also known as auditory processing)

Question 17

Higher and lower sounds differ in what?

Answer 17

Frequency (i.e. bees have high frequency, base drum has a low frequency)

Question 18

What is the range of frequency humans can hear?

Answer 18

20-20,000 hz

Question 19

What is basilar tuning?

Answer 19

1) hair cells in the cochlea allow brain to distinguish high and low frequencies
2) hair cell that matches the frequency of the sound will be activated
3) that particular hair cell is mapped to a particular region the primary auditory cortex (in the temporal lobe)- part of the brain that receives all info from the cochlea)
4) When activated, the hair cell will send an impulse down an axon, which eventually becomes a part of the auditory nerve
5) When the auditory nerve reaches the brain, the axons will separate to reach different parts of the primary auditory cortex of the brain
6) This allows for tonotopical mapping (each hair is mapped to a specific region of the primary auditory cortex that is sensitive to that specific frequency)
7) If we did not have the primary auditory cortex, we would not be able to distinguish sounds of different frequencies

Question 20

When are the hair cells at the base (start - 1600 hz) of cochlea activated?

Answer 20

high frequencies (low wavelength)

Question 21

When are the hair cells at the apex (end - 25 hz) of cochlea activated?

Answer 21

low frequencies (high wavelength)

Question 22

Cochlear Implants

Answer 22

surgical procedures to restore a degree of hearing (for individuals with sensorineural hearing loss)

Question 23

What is another name for sensorineural hearing loss?

Answer 23

Nerve deafness

Question 24

What is the major problem with people with sensorineural hearing loss?

Answer 24

Conduction of soundwaves from the cochlea to the brain

Question 25

What are the parts of a cochlear implant and how does it work?

Answer 25

microphone, speech processor, transmitter, receiver, and stimulator

1) Sounds enters microphone
2) Info goes to speech processor
3) Then to transmitter (outside of skull)
4) Then receiver (inside of the skull) which extends to the stimulator
5) Lastly Stimulator extends into the cochlea, which converts electrical impulses to neural impulses (which shoots down into the auditory nerve and into the brain to process the sound heard)