Sound (Audition)

Question 1

For us to hear sound we need two things (for audition to occur)

Answer 1

1. pressurized sound wave (a stimuli)
2. hair cell (a receptor, located in the cochlea)

Question 2

sound waves

Answer 2

Air molecules are pressurized and try to escape, creating areas of high and low pressure

Question 3

What are wavelength? short and higher

Answer 3

Wavelength: how close peaks are.
§ Smaller wavelength = greater frequency.
§ Higher wavelength (smaller frequency) = travel farther = penetrate
deeper into the cochlea.

Question 4

Sound (auditory waves) path:

Answer 4

1. First hit the outer part of the ear, known as the pinna.
2. Then the sound gets funneled from the pinna to the auditory canal (also known as
   external auditory meatus).
3. Then from the auditory canal they hit the tympanic membrane (also called the
   eardrum).
4. As a pressurized wave hits the eardrum, it vibrates back and forth, causing 3 bones to
   vibrate in this order: Malleus (hammer), incus (anvil), and Stapes (stirrups). *smallest bones, aka ossicles, acronym MIS
5. Stapes are attached to an oval window (aka elliptical window). The oval window then vibrates back and forth.
6. As it gets vibrated, it pushes fluid and causes it to go in/around cochlea (a round structure lined with hair cells).
7. At tip of cochlea (inner most part of circle), where can the fluid now go? It can only go back, but goes back to the round window (circular window) and pushes it out.
8. The reason doesn’t go back to oval window, is because in middle of cochlea is a membrane – the organ of Corti (includes the basilar membrane and the tectorial membrane)
9. As hair cells (cilia) move back and forth in the cochlea – an electric impulse is transported by the auditory nerve to the brain.
10. The above process of fluid going around the cochlea keeps occurring till the energy of the sound wave dissipates and stops moving. Occurs more = more hair cells vibrate.

Question 5

Place theory

Answer 5

our perception of sound depends on where each component frequently produces vibration along the basilar membrane.

one is able to hear different pitches because different sound waves trigger activity at different places along the cochlea basilar membrane

Question 6

External/Outer ear:

Answer 6

from pinna to tympanic membrane

Question 7

Middle ear

Answer 7

From malleus to stapes (three ossicles)

i. malleus (hammer)
ii. incus (anvil)
iii. stapes (stirrup)

Question 8

Inner ear:

Answer 8

Cochlea and semicircular canals

Question 9

Stapes – moving back and forth at same frequency as?

Answer 9

stimulus.
It pushes the elliptical window back and forth.

Question 10

Organ of Corti splits cochlea into 2

Answer 10

the upper and lower
membrane.

Question 11

At the upper membrane: The hair cells/cilia are called

Answer 11

hair bundle

Question 12

hair bundles are made up of?

Answer 12

little filaments. Each filament is called a kinocilium

Question 13

Tip of each kinocilium is connected by?

Answer 13

tip link which is attached to gate of K+ channel.

Question 14

When the tip links get pushed back and forth by endolymph movement, they stretch and allows

Answer 14

When the tip links get pushed back and forth by endolymph movement, they stretch and allows K+ to flow inside the cell from the endolymph

Question 15

Ca2+ role in upper membrane

Answer 15

Ca2+ cells get activated when K+ is inside, so Ca2+ also flows into the cell, and causes an AP, which then activates a spiral ganglion cell, which then activates the auditory nerve.

Question 16

We can hear frequencies between

Answer 16

20-20000Hz.

Question 17

How does the cochlea distinguish between sounds of varying frequencies and how is this distension maintained by the brain?

Answer 17

Auditory Processing:

Question 18

Brain uses basilar tuning. what is bsailar tuning

Answer 18

there are varying hair cells in the cochlea which allows the brain to distinguish between high and low-frequency sounds.

Question 19

Hair cells at base (start of
cochlea) of the cochlea are activated by (type of frequency)

Answer 19

activated by high-frequency sounds,
THNK: long wavelengths can travel farther.

Question 20

those at the apex (end of the cochlea) by are activated by (type of frequency)

Answer 20

by low-frequency sounds.
THNK: Long wavelengths can travel farther.

Question 21

Apex = what frequency and wavelength

Answer 21

Apex = 25 Hz (low freq, HIGH wavelength)

Question 22

Base = what frequency and wavelegnth

Answer 22

Base = 1600 Hz (high freq, LOW wavelength)

Question 23

Cochlear Implants:

Answer 23

A surgical procedure that attempts to restore some degree of
hearing to individuals with sensorineural narrow hearing loss – aka nerve deafness