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Infants' sensitivity to broadband noise.
1Department of Speech and Hearing Sciences, University of Washington, Seattle 98015-6246, USA.
The Journal of the Acoustical Society of America
|June 2, 2001
Summary
Infants show better hearing for broadband sounds compared to pure tones, unlike adults. This suggests infants may not use the same frequency-selective listening strategies as adults.
Area of Science:
- Auditory Perception
- Developmental Psychology
- Acoustics
Background:
- Infants exhibit higher pure-tone hearing thresholds than adults.
- A key hypothesis suggests infants' immature auditory sensitivity stems from a lack of frequency-selective listening strategies used by adults.
Purpose of the Study:
- To investigate infants' sensitivity to broadband sounds relative to adults.
- To test the prediction that infants are more sensitive to broadband sounds than pure tones, unlike adults.
Main Methods:
- Two experiments were conducted with 7-9-month-old infants and adults.
- Adaptive behavioral procedures were used to estimate unmasked and masked hearing thresholds for a 1000-Hz tone and broadband noise.
- Psychometric functions for broadband noise detection were also analyzed.
Main Results:
- The hearing threshold difference between infants and adults was smaller for broadband noise (7 dB unmasked, 5 dB masked) than for pure tones (14 dB unmasked, 10 dB masked).
- Infants' psychometric functions for broadband noise detection showed shallower slopes and lower upper asymptotes compared to adults', similar to tone detection.
- This indicates that improved broadband noise detection in infants is not attributable to increased attentiveness.
Conclusions:
- Infants' auditory processing of broadband sounds differs from adults', suggesting developmental differences in listening strategies.
- The findings support a model of infant sound detection that includes inattentiveness, listening strategy, and internal noise as contributing factors.