Lecture 19 Hearing in the Environment Flashcards

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1
Q

How are ITD values calculated based on tuning curves?

A

time to reach ipsilateral ear minus time to reach contralateral ear

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2
Q

What do positive ITD values on the tuning curve represent?

A

neurons that respond best to sounds that reach the CONTRALATERAL ear first

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3
Q

What do negative ITD values on the tuning curve represent?

A

neurons that respond best to sounds that reach the IPSILATERAL ear first

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4
Q

Why might IT tuning curves be broader in mammals than in birds?

A
  • mammals use population coding to encode ITD (to localize sound)
  • birds use specificity coding
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5
Q

TRUE or FALSE: neurons in the left hemisphere are tuned to respond most strongly to sounds reaching the left ear first

A

FALSE: LEFT hemisphere respond more strongly to sounds reaching RIGHT ear first

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6
Q

Area A1 is involved in ____________.

A

locating sound

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7
Q

What resulted when cat A1 areas were destroyed?

A

sound localization ability LOST

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8
Q

What resulted when ferret A1 was destroyed?

A

sound localization ability DECREASED

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9
Q

What resulted when cat A1 was cooled?

A

sound localization ability DECREASED

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10
Q

TRUE or FALES: the anterior belt area is also involved in locating sound

A

FALSE: the POSTERIOR BEST area involved in sound localization

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11
Q

TRUE or FALSE: posterior belt tuning curves are narrower than A1 tuning curves

A

TRUE (posterior belt single cell recordings revelaed neurons that only respond to sounds coming from particular locations in space –> SPECIFIC)

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12
Q

TRUE or FALSE: when the cat posterior belt was cooled, ability to differentiate 2 patterns of sound was impaired, but localization ability remained intact

A

FALSE: localization decreased; ability to differentiate 2 patterns intact

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13
Q

TRUE or FALSE: the posterior belt is involved in perceiving more complex sound

A

FALSE: anterior belt for complex sounds

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14
Q

What resulted when the cat anterior belt was cooled?

A

ability to differentiate between 2 patterns of sound decreased (localization unaffected)

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15
Q

Where, or dorsal stream, extends from the ________________ to the ____________ and ______________.

A

posterior belt; parietal lobe; frontal cortex

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16
Q

What, or ventral stream, extends from the ___________________ to the ___________________ and ______________.

A

anterior belt; temporal lobe; frontal cortex

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17
Q

What are the 2 kinds of sound waves that reach your ears?

A

direct and indirect sounds

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18
Q

What is a direct sound?

A

sound that reaches the listener’s ears straight from the source

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19
Q

What is an indirect sound?

A

sound that is REFLECTED off environmental surfaces and then to the listener

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20
Q

TRUE or FALSE: when a listener is inside a building, most sound is direct

A

FALSE:
- INSIDE building = both DIRECT and INDIRECT
- OUTSIDE = most sound is DIRECT

21
Q

What is the precedence effect? What does this imply about sounds that reach the ears at 2 different times?

A
  • when sound comes from lead speaker followed by lag speaker with a LONG DELAY, listener hears 2 sounds
  • when delay is decreased to 5-20 msec, listener hears sound only coming from LEAD SPEAKER
  • reflects a threshold for attributing differences in timing –> SLIGHT DIFFERENCES IN DIRECT AND INDIRECT SOUND WAVES REACHING OUR EARS doesn’t lead to perception of distinct sounds
22
Q

What are architectural acoustics? Provide an example

A

study of how sounds are reflected in rooms (e.g. how the design of concert halls influence the perception of sound)

23
Q

What is reverberation time?

A

the time it takes sound to decrease to 1/1000th of its original pressure

24
Q

How does sound seem if reverberation time is too long? too short?

A
  • too long = muddled
  • too short = dead
25
Q

What is the ideal reverberation time?

A

2 seconds

26
Q

What are some factors related to room design that affect perception of sound?

A
  • intimacy time
  • reverberation time
  • bass ratio
  • spaciousness factor
27
Q

What is intimacy time?

A

time between when sound leaves its source and when the FIRST REFLECTION ARRIVES

28
Q

What is the best intimacy time?

A

20 ms

29
Q

What is bass ratio?

A

ratio of LOW TO MIDDLE FREQUENCIES reflected from surfaces

30
Q

What is the best bass ratio?

A

high bass ratio

31
Q

What is spaciousness factor?

A

fraction of ALL SOUND received by listener that is INDIRECT

32
Q

What is the best spaciousness factor?

A

high spaciousness factor

33
Q

What is an auditory scene?

A

the array of all sound sources in the environment

34
Q

What is auditory scene analysis?

A

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

35
Q

Why does auditory scene analysis not occur in the cochlea?

A

simultaneous sounds are processed together in the pattern of vibration of the basilar membrane (i.e. does not separate sounds)

36
Q

What is does onset time tell us?

A

sounds that start at different times are likely to come from different sources

37
Q

What can we infer about location when separating sound sources?

A

a single sound source tends to come from ONE LOCATION and moves in a SMOOTH and continuous way

38
Q

What can we infer from similarity of timbre and pitch? Provide an example.

A

similar sounds are grouped together (e.g. a flute will typically continue sounding like a flute throughout an entire piece of music)

39
Q

What is implied polyphony? What are some other names for it?

A
  • when a single instrument alternates rapidly between streams of low and high notes, the listener perceives it as 2 separate melodies
  • i.e. compound melodic lines OR auditory stream segregation
40
Q

TRUE or FALSE: when stimuli are played slowly, the listener perceives high and low tones as 2 separate alternating streams

A

FALSE:
- slow= high and low tones alternating within a SINGLE STREAM
- fast = 2 SEPARATE STREAMS, one high and one low

41
Q

What is the scale illusion?

A
  • stimuli were 2 sequences alternating between right and left ears
  • listeners perceive 2 smooth sequences by grouping sounds by similarity in PITCH
  • because sound with same frequency usually come from same source, this heuristic allows us to accurately separate sound sources
42
Q

What does proximity in time tell us about sounds?

A

sounds that occur in rapid succession usually come from the same source

43
Q

What does auditory continuity tell us about sounds?

A

sounds that stay constant or change smoothly are usually from the same source

44
Q

How does melody schema affect sound perception?

A

prior experience and memory affect how we interpret melodies

45
Q

What is the ventriloquist effect? What does it tell us about the relation between vision and audition?

A
  • occurs when an observer incorrectly perceives a sound as coming from a location suggested by visual information
  • i.e. VISION SUPERSEDES AUDITION
46
Q

What is the two flash illusion? What does it tell us about the relationship between audition and vision?

A
  • seeing a single dot flash on screen is misinterpreted as two flashed dots IF ACCOMPANIED BY 2 BEEPS
  • i.e. AUDITION SUPERSEDES VISION
47
Q

What are coordinated receptive fields? Provide an example.

A
  • neurons which respond to multimodal stimuli (e.g. sound and vision) that originate in common regions of space
  • e.g. a neuron in parietal lobe respond to visual info in the lower left of visual field, and sounds coming from the same point in space
48
Q

When blind echolocators created clicking sounds, how did the visual cortex in blind participants and non-blind participants respond?

A
  • activate visual cortex in blind participants
  • no activation of visual cortex in normal vision participants