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HESP722 Final > Spatial Perception > Flashcards

Spatial Perception Flashcards

1
Q

Define monaural.

A

-One ear

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2
Q

Define binaural.

A

-Two ears

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3
Q

Define diotic.

A

-Same signal to both ears

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4
Q

Define dichotic.

A

-Different signals across ears

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5
Q

What is Duplex Theory?

A
  • Humans can use ITDs and ILDs to help localize sounds
  • ILDs are best at pure tone frequencies above 1.5 kHz
  • ITDs are best at pure tone frequencies below 1.5 kHz
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6
Q

What are the caveats to Duplex Theory?

A
  • ILDs: tuned to all frequencies with lateralization (i.e. under headphones)
  • ITDs: used for frequencies above 1.5 Hz in complex waveforms (i.e. AM)
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7
Q

Describe ITD processing in terms of straightness and centrality.

A
  • With regard to neural firing in a Jeffris matrix
  • Straightness: all firing neurons lined up across frequencies
  • Centrality: neurons firing near midline matter more than those that are more lateral
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8
Q

Describe ILDs and MAAs as a function of frequency.

A

-Minimum audible angle (MAA): smallest detectable change in azimuthal position
(best in front, worse on the side)
-Bump around 1500 Hz due to “bright spot” due to the human head interfering with the traveling wave
-Affects are more noticeable as angle lateralizes

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9
Q

Describe frequency importance regions for horizontal and vertical plane localization.

A

-Elevation: pinnae cues are frequency-dependent

Horizontal: depends (ITDs are frequency-independent but ILDs are frequency-dependent)

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10
Q

What are head-related transfer functions (HRTFs)?

A
  • Composed of ITDs, ILDs, and spectral cues
  • ITDs and ILDs are very similar across people but spectral cues can be very different
  • If you remove characteristic filtering from HRTFs, then sound can become internalized and harder to localize
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11
Q

Explain the barbershop demonstration.

A
  • Filtered the sounds with the HRTFs (ILDs, ITDs, and spectral cues)
  • Everybody’s head is about the same size, so the ITDs and ILDs work for everyone
  • Good left-right discrimination
  • But, not everybody’s pinna is the same
  • Strong filtering agent (spectral cues) for elevation
  • Some people will do better with up-down and front-back discrimination
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12
Q

What is the precedence effect?

A

-When two sounds are presented sequentially but sufficiently close together in time, the perceived location of the two sounds will be dominated by that of the initial sound

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13
Q

What is spatial release from masking?

A

-When a masker is a similar pitch to the target, forcing the listener to rely solely on spatial cues which minimizes the effects of the masker

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14
Q

What is evidence for spatial release from masking?

A
  • Bernstein et al. (2016)
  • Spatial release from masking can occur when an interferer is simultaneously introduced with a target signal and the interferer
  • Observed in an experiment in which listener performance on a task improves when the target is simultaneously presented with 2 interferers as opposed to 1 interferer
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15
Q

What is monaural head shadow effect?

A
  • Better SNR in one ear (~6 dB)

- Accessible to NH, HI, and CI users now

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16
Q

What is evidence for monaural head shadow effect?

A

-Early/long deaf BICI users only get 1 dB of head shadow benefit whereas acoustic hearing listeners get 6 dB of benefit

17
Q

What is binaural unmasking?

A
  • Added advantage from neural processing and auditory stream segregation
  • NH listeners are good at this
  • What we want CI users to do better
18
Q

What is evidence for binaural unmasking?

A
  • Some BICI listeners experience binaural unmasking, but some experience interference
  • Bernstein et al. (2016): Speech understanding performance improved with 2 CIs as opposed to 1 CI
  • Goupell et al. (submitted): However, early/long deafness listeners only get 1 dB of head shadow not 6 dB
19
Q

What is binaural masking level difference?

A
  • Measure of the improvement in detectability of a sound that can occur under binaural listening conditions
  • The difference in threshold of the signal (dB) for the case where the signal and masker have the same phase/level at both ears and the case where the interaural phase/level relationships of the signal and masker are different
20
Q

What is the effect of CF on binaural masking level difference?

A

-Higher CFs should yield lager BMLDs because they have broader filters

21
Q

What is the effect of BW on binaural masking level difference?

A

-Both YNH and ONH listeners experienced greater BLMDs in NoSpi and NpiSo conditions for wideband stimuli compared to narrowband stimuli

22
Q

Describe plasticity for vertical plane sound localization.

A
  • Ears can re-learn vertical plane localization cues
  • Hofman et al. (1998) had participants wear custom earmolds for 6 weeks
  • Pre-testing showed left/right and up/down localization
  • Ears adapted to cues from earmolds (only left/right localization)
  • Once earmolds were removed, pinna cues returned to pre-earmold
23
Q

Describe hearing loss for vertical plane sound localization.

A
  • Despite significant AR HFHL, older adults are able to accurately localize sounds in the azimuth direction (suggests that binaural sound localization doesn’t deteriorate with age)
  • Older adults with large ears and HFHL demonstrated improvement in elevation localization
  • Maybe ears get bigger to combat the fact that you’re going to get AR HFHL

HESP722 Final (5 decks)

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