Sound source segregation

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Sound source segregation

• Development of the ability to separate concurrent
  sounds into auditory objects

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The problem
Wow! Psychophysics is interesting!
TIME
FREQUENCY
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Cues that adults use to segregate components into
sources

• Spectral separation
• Spectral profile
• Harmonicity
• Spatial separation
• Temporal separation
• Temporal onsets and offsets
• Temporal modulations

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Measuring sound source segregation

• Auditory streaming
• Thresholds of sounds, segregated and not
  segregated
• Informational masking (indirect evidence)

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Auditory streaming
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A single sound source is perceived
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Two sound sources are perceived
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Auditory streaming in infants
How many streams that time?
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Auditory streaming in infants
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Auditory streaming in infants
Configuration 3/1
Configuration 2/2
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Electrophysiological measures of streaming in
newborns
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(No Transcript)
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Auditory streaming in children
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Auditory streaming in children
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Another way to look at auditory streaming in
children
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Electrophysiological measures of streaming in
children
Electrophysiological measures of streaming in
children
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Conclusion

• Infants and children form auditory streams.

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Thresholds of sound, segregated and not segregated

• Spatial cues
• Synchronized visual information

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Masking level difference
The MLD is the improvement in audibility that
results from dichotic listening
N noise, S signal Monotic one ear
(m) Diotic 2 ears, same sound in both
(0) Dichotic 2 ears, different sound in each
(p)
Modified from Gelfand (1998)
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MLD in infants
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MLD in children
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Spatial unmasking
(noise)
Baseball
(noise)
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Spatial unmasking in preschool children
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Spatial unmasking in school-age children
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Preferential looking procedure
baseball, baseball, baseball
popcorn, popcorn, popcorn
baseball, baseball, baseball
(Twenty subjects were tested)
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Speech in speech recognition in infants
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Visual information improves speech in speech
recognition in infants
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Testing whether children can segregate speech
from speech
Ready Baron go to Blue 3 now Ready Ringo go to
Red 5 now
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Visual information doesnt improve speech in
speech recognition in children
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Conclusions

• Infants and children are more sensitive to sounds
  that can be segregated from competing sounds,
  although infants show less benefit of segregation
  cues.
• Under simple conditions, even 3-year-olds can use
  segregation cues as well as adults.
• Under complex conditions, even 10-year-olds do
  not use segregation cues as well as adults.

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Informational masking
Interval 1
Interval 2
Trial
1
Level
2
3
Frequency
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Informational masking in children
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Informational masking in infants
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Information masking in infants
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Fixed, remote frequency masking in children
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Informational masking?
Interval 1
Interval 2
Trial
1
Level
2
3
Frequency
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Using temporal cues to reduce informational
masking
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Summary and conclusions

• Infants and children can segregate sound sources,
  using the same acoustic cues that adults use.
• In simple situations, children, but not infants,
  can segregate sound sources as well as adults.
• In complex situations, sound source segregation
  may not be mature until well into the school
  years.