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Updated: Aug 12, 2026
P50 Sensory Gating in Infants
Published on: December 26, 2013
Infants' sensitivity to broadband noise
1Department of Speech and Hearing Sciences, University of Washington, Seattle 98015-6246, USA.
Insights
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.
Abstract:
Infants have higher pure-tone thresholds than adults. One explanation is that infants do not adopt the frequency-selective listening strategy that adults use when detecting tones. In contrast to other models of infants' immature sensitivity, the listening strategy account predicts that infants will be more sensitive to broadband sounds, relative to adults. Infants 7-9 months old were tested in two experiments to examine their sensitivity to broadband noise. Unmasked and masked thresholds for a 1000-Hz tone and for broadband noise were estimated adaptively for infants and adults using an observer-based behavioral procedure. The difference between infants and adults in unmasked threshold were 14 and 7 dB for tones and noise, respectively. The difference between infants and adults in masked threshold were 10 and 5 dB for tones and noise, respectively. Psychometric functions for detection of broadband noise were also obtained from some infants and adults. Infants' psychometric functions were similar to those obtained in tone detection with shallower slopes and lower upper asymptotes than adults'. This suggests that the relative improvement in infants' threshold for broadband noise is not due to greater attentiveness to the noise. A model of infants' sound detection invoking inattentiveness, listening strategy, and an unspecified source of internal noise may account for the characteristics of the infant psychometric function.
