2. Sound source segregation Development of the ability to separate concurrent sounds into auditory objects

3. The problem… TIME FREQUENCY Wow! Psychophysics is interesting!

4. Cues that adults use to segregate components into sources Spectral separation Spectral profile Harmonicity Spatial separation Temporal separation Temporal onsets and offsets Temporal modulations

5. Measuring sound source segregation Auditory streaming “Thresholds” of sounds, segregated and not segregated Informational masking (indirect evidence)

6. Auditory streaming

7. A single sound source is perceived

8. Two sound sources are perceived

9. Auditory streaming in infants How many streams that time?

10. Auditory streaming in infants

11. Configuration 3/1 Configuration 2/2

12. Electrophysiological measures of streaming in newborns

14. Auditory streaming in children

16. Another way to look at auditory streaming in children

17. Electrophysiological measures of streaming in children

18. Conclusion Infants and children form “auditory streams.”

19. Thresholds of sound, segregated and not segregated Spatial cues Synchronized visual information

20. 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 (π) Modified from Gelfand (1998)

21. MLD in infants

22. MLD in children

23. Spatial unmasking Baseball (noise)

24. Spatial unmasking in preschool children

25. Spatial unmasking in school-age children

26. Preferential looking procedure baseball, baseball, baseball (“Twenty subjects were tested…”) baseball, baseball, baseball popcorn, popcorn, popcorn

27. Speech in speech recognition in infants

28. Visual information improves speech in speech recognition in infants

29. Testing whether children can segregate speech from speech Ready Baron go to Blue 3 now Ready Ringo go to Red 5 now

30. Visual information doesn’t improve speech in speech recognition in children

31. 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.

32. Informational masking Interval 1 Interval 2 Level Frequency Trial 1 2 3

33. Informational masking in children

34. Informational masking in infants

35. Information masking in infants

36. Fixed, remote frequency masking in children

37. Informational masking? Interval 2 Level Frequency Trial 1 2 3 Interval 1

38. Using temporal cues to reduce informational masking

39. 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.