Topic 10: Auditory Localization and Organization

Question 1

visual vs auditory localization

Answer 1

3d world to 0D acoustic signal that varies in time

location in cochlea shows frequency of sound

Question 2

auditory localization

Answer 2

task of determing source of sounds in auditory space

Question 3

azimuth coordinates
elevation coordinates
distance coordinates

Answer 3

position L or R (easiest)
position up or down
how far is sound from observer

Question 4

interaural level difference

Answer 4

binaural cue - needs both ears
difference in amplitude between 2 ears - clear path for one ear and other is blocked (head as acoustic barrier)
works for high frequency, has higher shadow and low bends around corner

Question 5

Interaural time difference

Answer 5

binaural cue - needs both ears
difference in arrival time (phase) between ears based on location
due to difference in distance from sound source
if directly in front it will arrive equally
difference in sounds setting to peak - rise/fall of pressure waves is out of sync/phase

Question 6

cones of confusion

Answer 6

ILD and ITD help determine azimuthal (L/R) direction
sounds coming straight from L is easy to detect
any point along body midline will be equidistant and unshadowed for both ears (same arrival time)
smaller cones of confusion further to sides

Question 7

spectral cue

Answer 7

monaural cue - only requires one ear
sounds coming from different directions bounce of pinna in different ways
different signature based on elevation

Question 8

King et al : spectral cue

Answer 8

P had eyes closed and ID whole sounds came from - initial sound location performance are accurate

• with pinna mold - elevation localization impaired due to impaired spectral cue
• performance with mold recovers by day 19 - new spectral cues are learned

Question 9

Neural coincidence detectors

Answer 9

-only fire when both inputs occur at the same time - ITD detectors
-if it arrives to a farther left neuron it means it came from the right
set of detectors for both L and R side
narrow curve for birds and broad for mammals

Question 10

Cortical areas involved in localization

Answer 10

-A1 core
posterior areas of belt
partietal where stream
posterior area deactivated –> cant locate sounds can ID
anterior deactivated –> can locate but not ID

Question 11

auditory scene

auditory scene analysis

Answer 11

array of all sound sources in enviornment

-process by which sound sources in auditory scene are separated into individual perceptions

Question 12

sound location

Answer 12

determined by ITD and ILD and spectral cues
sounds from same location are grouped
sounds from different locations are separated

Question 13

onset and offset times

Answer 13

sounds that start/emd at same time are grouped
sounds that start/end at different times are separated
harmonic changing at different rate is perceived differently

Question 14

temporal proximity

Answer 14

sounds near in time tend to be percieved as a group

low high low

Question 15

pitch and organizing principles

Answer 15

sounds similar in pitch tend to be perceived as a group
auditory stream segregation
when they pass through each other they are grouped
X

Question 16

temporal proximity and pitch

Answer 16

principles trade off based on speed and pitch
very different pitches tend to segregate as tempo increases
very similar pithces tend to stay grouped together as tempo increases

Question 17

timbre

Answer 17

sounds with same timbre tend to be grouped
wessel demonstration - timbre and temporal proximity tradeoff
players using same instrument - we dont hear it as 2 distinct sounds - single stream (same timbre)

Question 18

auditory continuity

Answer 18

auditory analog of good continuation
when noise bursts matches tones in level, we perceive tone continuing behind noise
picket fence with speech

Question 19

experience

Answer 19

past experience and expectations influence auditory perception
phenomic restoration - cough makes it seem like nothing is missing
when silence we know whats missing

Question 20

chromesthesia

Answer 20

sound to colour (auditory - visual) synesthesia
sounds create perception of colour (in moment)
involuntary and instantaneous
1/3000 - van gogh

Question 21

synesthesia

Answer 21

1 type of perceptual phenomenon as a result of different type of sensory stimulus
developmental from birth, 1/2000
automatic
more common among children, more common in women

Question 22

sound colour matches (ward et al)

Answer 22

synaesthete - highly consistent of colour perception across two tests when presented with a tone
control group was inconsistent which shows the perception is automatic

Question 23

cross-modal stroop interference

Answer 23

task: p’s name colour that seeing whle hearing tone
tone was same time as colour or 150ms after
colour and tone was either congruent or incongruent with previous perception reports
synaesthete - significant stroop effect , incongruent trials led to interference and slower rxn time

Question 24

possible mechanisms of stroop interfernce

Answer 24

1. atypical direct connections between processing perceptual modalities, direction connections between A and V systems
2. typical feedback pathways via multimodal convergence areas, high processing level and feedback into low visual areas

Question 25

Neufeld et al: fMRI evidence

Answer 25

had P’s and control and listen to sounds
synaesthetes showed higher acitvation in L inferior parietal cortex (IPC) - area involved in multimodal processing
integration of auditory and visual at higher processing levels