week 8 - anatomy of the ear

Question 1

condensation

Answer 1

• increase in pressure
• molecules are closer to each other

Question 2

rarefaction

Answer 2

• decrease in pressure
• molecules are further from each other

Question 3

What are the physical aspects of sound?

Answer 3

• amplitude
• frequency

Question 4

amplitude

Answer 4

• size of pressure wave
• high amplitude = loud
• low amplitude = quiet

Question 5

frequency

Answer 5

• number of cycles per second
• high frequency = high pitch
• low frequency = low pitch

Question 6

What are the perceptual aspects of sound?

Answer 6

• loudness
• pitch
• timbre

Question 7

loudness

Answer 7

• the perceptual quality most closely related to amplitude
• measured in decibels

Question 8

pitch

Answer 8

the perceptual quality we describe as high/low

Question 9

timbre

Answer 9

• all other perceptual aspects of sound
• ex.) being able to tell the difference between two instruments

Question 10

outer ear

Answer 10

contains pinna and external auditory canal

Question 11

pinna

Answer 11

contributes to sound localization

Question 12

external auditory canal

Answer 12

tube filled with protective hair and wax

Question 13

middle ear

Answer 13

includes the tympanic membrane, ossicles, and oval window

Question 14

tympanic membrane

Answer 14

• border between middle and outer ear (ear drum)
• vibrates at the same frequency of sound coming in
• allows our ossicles to vibrate

Question 15

ossciles

Answer 15

• vibrate at a higher intensity to knock oval window and move fluid behind it
• hammer -> anvil _> stirrup

Question 16

oval window

Answer 16

membrane-covered opening between middle and inner ear that knocks at fluid inside cochlea

Question 17

inner ear

Answer 17

contains the cochlea

Question 18

cochlea

Answer 18

contains 3 tubes
- scala vestibuli
- scala media
- scala tympani

Question 19

Which cochlear tube does reception occur through hair cells (cilia) and has the most action take place?

Answer 19

scala media

Question 20

How does cilia activate transduction?

Answer 20

• cilia must move in a certain direction in order to open to open ion channels
• opening of cilia allows calcium to move inside cell and activate an action potential
• action potential = transduction

Question 21

How do neurons make up for nerve firing to a sound stimulus during refractory periods?

Answer 21

• multiple neural responses are needed in order to encompass all frequencies
• creates a cranial nerve

Question 22

cranial nerve

Answer 22

collection of nerve fibers

Question 23

What two theories are believed to code for pitch perception?

Answer 23

• frequency theory
• place theory

Question 24

frequency theory

Answer 24

• basiliar membrane vibrates in synchrony with sound
• auditory nerve produces action potential at the same frequency

Question 25

What are the physical properties of the basilar membrane?

Answer 25

narrow up until apex where it is the thickest

Question 26

place theory

Answer 26

• frequency of sound is indicated by the place along the basilar membrane
• each area is tuned to a specific frequency

Question 27

auditory space

Answer 27

surrounds an observer and exists wherever there is sound

Question 28

Azimuth coordinates

Answer 28

• left-right

Question 29

elevation coordinates

Answer 29

• up-down

Question 30

distance coordinates

Answer 30

position from observer

Question 31

binaural cue

Answer 31

location cues based on the comparison of the signals by the left/right ears

Question 32

interaural time difference (ITD)

Answer 32

• no differences in time when distance to each ear is the same
• time differes when source is one one side of the observer

Question 33

internaural level difference (ILD)

Answer 33

• difference in air pressure
• if sound is louder in one ear, sound is most likely coming from that side

Question 34

monaural cue

Answer 34

• uses information from one ear
• reliant on pinna

Question 35

Describe the pinna experiment on monaural cues

Answer 35

• microphones were placed in ears to measure how sound bounces off location of ear
• different sound in different locations (above vs. below aka elevation)

Question 36

spectral cues

Answer 36

elevation coordinate, especially at higher frequencies

Question 37

spectral cues experiment

Answer 37

• molds were placed in ears to measure spectral cues for a period of time
• brain gets used to mold over time; performance high after removal
• suggests there are two sets of neurons - one for each set of cues

Question 38

What type of cues work best for azimuth coordinate?

Answer 38

ITDs and ILDs

Question 39

What type of cues work best for low frequencies?

Answer 39

ITD

Question 40

What type of cues work best for high frequencies?

Answer 40

ILD