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Updated: Jun 3, 2026
Behavioral Assessment of Hearing in 2 to 4 Year-old Children: A Two-interval, Observer-based Procedure Using Conditioned Play-based Responses
Published on: January 23, 2017
Behavioral bone-conduction thresholds for infants with normal hearing
Lauren R Hulecki1, Susan A Small
1School of Audiology and Speech Sciences, University of British Columbia, Vancouver, Canada.
Insights
Infants under 30 months exhibit a maturational air-bone gap in low-frequency bone-conduction hearing, persisting until at least 30 months of age. This necessitates distinct normal levels for behavioral assessments in infants.
Area of Science:
- Audiology
- Pediatric Hearing Assessment
- Auditory Development
Background:
- Bone-conduction thresholds are crucial for differentiating hearing loss types in infants and adults.
- Physiological measures in infants reveal a low-frequency maturational air-bone gap due to auditory system development, not conductive impairment.
- This gap persists up to 2 years, necessitating investigation into behavioral assessment methods.
Purpose of the Study:
- To estimate behavioral bone-conduction thresholds in infants using visual reinforcement audiometry (VRA).
- To determine if frequency-dependent maturational patterns, similar to physiological findings, exist for behavioral bone-conduction thresholds.
- To assess the presence and extent of a maturational air-bone gap in young children's behavioral hearing assessments.
Main Methods:
- Behavioral bone-conduction minimum response levels were measured using VRA at 500, 1000, 2000, and 4000 Hz.
- Two infant groups were assessed: younger (7-15 months) and older (18-30 months), all screened for low hearing loss risk.
- Data analysis involved calculating 90th percentile normal levels, mixed-model ANOVA for group and frequency comparisons, and linear regression for age effects.
Main Results:
- Infants under 30 months demonstrated frequency-dependent behavioral bone-conduction thresholds, with better responses at 500/1000 Hz than 2000/4000 Hz.
- No significant difference in bone-conduction thresholds was found between the younger (mean 10.6 months) and older (mean 23.0 months) infant groups at any frequency.
- A maturational air-bone gap was observed in the low frequencies when compared to established infant air-conduction thresholds.
Conclusions:
- Behavioral bone-conduction thresholds in infants under 30 months mirror findings from physiological studies.
- A maturational air-bone gap persists in low frequencies until at least 30 months of age.
- Different normal hearing levels are recommended for behavioral bone-conduction assessments in infants compared to adults.
Background:
Bone-conduction thresholds have been used in audiologic assessments of both infants and adults to differentiate between conductive and sensorineural hearing losses. However, air- and bone-conduction thresholds estimated for infants with normal hearing using physiological measures have identified an "air-bone gap" in the low frequencies that does not result from conductive hearing impairment but, rather, from maturational differences in sensitivity. This maturational air-bone gap appears to be present up to at least 2 yr of age. Because most infants older than 6 mo of age are clinically assessed behaviorally, rather than physiologically, it is necessary to determine whether a similar maturational air-bone gap is present for behavioral air- and bone-conduction thresholds.
Purpose:
The purpose of this study was to estimate behavioral bone-conduction thresholds for infants using a standard clinical visual reinforcement audiometry (VRA) protocol to determine whether frequency-dependent maturational patterns exist as previously reported for physiological bone-conduction thresholds.
Research Design:
Behavioral bone-conduction minimum response levels were estimated at 500, 1000, 2000, and 4000 Hz using VRA for each participant.
Study Sample:
Young (7-15 mo; N = 17) and older (18-30 mo; N = 20) groups of infants were assessed. All infants were screened and considered to be at low risk for hearing loss.
Data Collection And Analysis:
Preliminary "normal levels" were determined by calculating the 90th percentile for responses present as a cumulative percentage. Mean bone-conduction thresholds were compared and analyzed using a mixed-model analysis of variance across frequency and age group. Linear regression analysis was also performed to assess the effect of age on bone-conduction thresholds.
Results:
Results of this study indicate that, when measured behaviorally, infants under 30 mo of age show frequency-dependent bone-conduction thresholds whereby their responses at 500 and 1000 Hz are significantly better than those at 2000 and 4000 Hz. However, thresholds obtained from the younger group of infants (mean age of 10.6 mo) were not significantly different from those obtained from the older group of infants (mean age of 23.0 mo) at any frequency.
Conclusions:
The findings of the present study are similar to the results obtained from previous physiological studies. Compared to previously documented air-conduction thresholds of infants using similar VRA techniques, a maturational air-bone gap is observed in the low frequencies. Therefore, differences between infant and adult bone-conduction thresholds persist until at least 30 mo of age. As a result, different "normal levels" should be used when assessing bone-conduction hearing sensitivity of infants using behavioral methods.
