auditory processing part 1

Question 1

visual vs auditory localization

Answer 1

vision: 3D world to 2D retinal image
- retinal image = location in space
audition: 3D world to 0D accoustic signal
- location in cochlea = frequency of sound

Question 2

auditory localization

Answer 2

task of determining source of sounds in auditory space

Question 3

azimuth localization

Answer 3

coordinate positions left to right

Question 4

elevation localization

Answer 4

coordinates position up and down

Question 5

distance localization

Answer 5

coordinates position from observer

Question 6

interaural level difference

Answer 6

ILD:
- binaural cue requires both ears
- difference in amplitude between ears
- head acts as a barrier creating accoustic shadow
best for high frequeuncy (more trouble getting around)

Question 7

interaural time difference

Answer 7

ITD:
- binaural cue requires both ears
- difference in time (phase) between ears
- caused by difference in distance from sound source to ears
best for low frequencys (waves are bigger easier to detect difference)

Question 8

cones of confusion

Answer 8

ILD and ITD help determine azimuthal direction
not helpful for elevation and distance
any point along midline is equidistant and unshadowed for both ears
cones of confusion are smaller furthur to sides

Question 9

spectral cue

Answer 9

• monaural cue requires one ear

- sounds coming from different directions bounce of pinna in different ways depending on shape of pinna

Question 10

spectral cue experiment

Answer 10

used a mold to modify pinna
- at first azimuth location was intact and elevation was impaired
- by day 19 performance was recovered
perceptual system learns new spectral cues from new ear

Question 11

jeffress neural coincidence model

Answer 11

explains ITD medial superior olive
- coincidence detectors that only fire when both inputs occur at the same time
- indicated by which neuorn fires
ex. neuron 1 is far right, 5 is middle, 9 is far left
have tuning curves: each cell tuned for a particular time difference

Question 12

ITD in animals

Answer 12

owls and birds have narrow ITD tuning curves
- represented by which neuron fires
- place code
gerbils and mammals have broad ITD curves
- represented by firing of many neurons
- population code

Question 13

which cortical areas are involved in localization

Answer 13

A1 core
posterior belt
dorsal where stream

Question 14

what happens when the where/what pathways are deactivated

Answer 14

where- cant locate sounds but can identify

what- cant identify sounds but can locate

Question 15

how do we seperate sound?

auditory scene analysis

Answer 15

auditory scene: array of all sound sources in environment
auditory scene analysis: seperation of sound sources within a scene
ex. applause, barking, bell, water
- organizing principles are similar to Gestalt

Question 16

onset and offset time

Answer 16

sounds that start/end at the same time are grouped

sounds that start/end at different times are seperated

Question 17

temporal proximity

Answer 17

sounds near in time tend to be perceived as a group

Question 18

location of sound

Answer 18

• determined using ITD, ILD and spectral cues
  sounds from the same source are grouped
  sounds from different sources are seperated

Question 19

pitch

Answer 19

sounds similar in pitch tend to be perceived as a group

• when sequences are distant, segregation occurs
• as sequeneces pass through eachother, grouping occurs

Question 20

temporal proximity vs pitch

Answer 20

trade off based on speed and pitch

• different pitches segregate as tempo increases
• similar pitches tend to stay grouped as tempo increases

Question 21

timbre

Answer 21

sounds with the same timbre tend to be grouped

Question 22

auditory continuity

Answer 22

good continuation
- when noise bursts matches tones in level, we perceive tone continuing “behind noise”
picket fence effect

Question 23

experience

Answer 23

past experience and expectations influence auditory perception

Question 24

phonemic restoration

Answer 24

when a phenome is replaced by a cough nothing is perceived to be missing
when a phenome is replaced by silence missing phenome can be perceived

Question 25

multi-tone masking

Answer 25

once youve heard the beeps alone it is easier to hear beeps in a sequence of noises
experience has been changed and youre able to pick up regular sequence burried in noise

Question 26

laurel vs yanny

Answer 26

have vary similar features

ambiguous sound is a blend of both

Question 27

all auditory scene analysis factors

Answer 27

location, on/offset time, temporal proximity, pitch similarity, timbre similarity, auditory continuity, experience

Question 28

chromesthesia

Answer 28

sound to color (auditory-visual) synesthesia
- sounds create a perception of color, involuntarily and instantaneously
1/3000 people have it

Question 29

types of synesthesia

Answer 29

grapheme- color (letter--> color)
spatial sequence (number --> spatial location)
auditory- tactile (sound --> touch)
lexical gustatory (word--> taste)
flavor- color (taste--> color)
pain- color

Question 30

sound-color matches experiment

Answer 30

synaesthate had highly consistant colors across two tests

- sounds evoked very similar colors compared to control

Question 31

cross-modal stroop interference

Answer 31

participants had to name a color while hearing a tone

• found that synthestes were slower to say the color words on incongruent trials than one congruant
• no effect in control

Question 32

possible mechanisms of synesthesia

Answer 32

1. direct connections between areas processing perception

2. typical feedback pathways via multimodal convergence

Question 33

fMRI evidence

Answer 33

increased activation in left inferior parietal cortex

• area involved in multimodal integration
• suggests long pathway through multimodal area for feedback