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Behavioral thresholds for tones during infancy
Insights
Infants aged 6 to 18 months show developing auditory sensitivity. While younger infants struggle with high frequencies, older infants demonstrate adult-like hearing across tested frequencies.
Area of Science:
- Audiology
- Developmental Psychology
- Acoustics
Background:
- Auditory development in infants is crucial for speech perception and language acquisition.
- Understanding auditory sensitivity across different frequencies in early childhood is essential for identifying potential hearing impairments.
Purpose of the Study:
- To assess auditory sensitivity to pure-tone stimuli at 500, 2000, and 8000 Hz in infants aged 6 to 18 months.
- To compare auditory thresholds between different age groups and testing conditions (headphones vs. sound field).
Main Methods:
- Utilized an adaptive up-down tracking procedure combined with a visually reinforced head turn response.
- Tested infants using headphone presentation (6- and 10-month-olds) and sound field presentation (10-, 14-, and 18-month-olds).
Main Results:
- Infant auditory threshold estimates were comparable to adult values across all tested frequencies and age groups (within 15 dB).
- Six-month-olds exhibited significantly reduced sensitivity to 8000-Hz tones compared to lower frequencies.
- Older infants (10-18 months) showed similar auditory sensitivity across all three tested frequencies.
Conclusions:
- Infant auditory sensitivity develops significantly between 6 and 18 months of age.
- High-frequency hearing (8000 Hz) matures later than lower frequencies in early infancy.
- The study confirms reliable methods for assessing infant auditory thresholds in both headphone and sound field conditions.
Abstract:
An adaptive up-down tracking procedure was used in combination with a visually reinforced head turn response to examine auditory sensitivity for 500, 2000, and 8000-Hz tone bursts in infants 6 to 18 months of age. Six- and 10-month-old infants were tested with headphone presentation of stimuli, while 10-, 14-, and 18-month-olds were tested in sound field. Infant threshold estimates for both headphone and sound field were within 15 dB of adult comparisons for all frequencies and age groups. Six-month-olds were significantly less sensitive to the 8000-Hz tone than to either of the lower frequency stimuli, but older infants demonstrated approximately equal sensitivity for all three frequencies tested.