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Infant Auditory Processing and Event-related Brain Oscillations
Published on: July 1, 2015
Distortion product otoacoustic emissions during the first year in term infants: a longitudinal study
1Children's Hospital, Fudan University, Shanghai, China.
Insights
Distortion product otoacoustic emissions (DPOAEs) in infants show high pass rates at high frequencies but low rates at low frequencies. Age-related changes in DPOAE levels are minimal, but interpretation requires considering infant age and frequency.
Area of Science:
- Pediatric audiology
- Otoacoustic emissions research
- Infant hearing screening
Background:
- Distortion product otoacoustic emissions (DPOAEs) are crucial for detecting cochlear impairments in infants.
- Understanding age-related DPOAE variations in infancy is vital for accurate hearing assessments.
- Longitudinal infant DPOAE data is essential for establishing normative values.
Purpose of the Study:
- To investigate age-related differences in DPOAEs during the first year of life in normal-hearing infants.
- To determine the impact of infant age on DPOAE pass rates and levels across various frequencies.
- To inform the interpretation of DPOAE results for infant hearing screening.
Main Methods:
- Longitudinal study of DPOAEs in 70 ears of 35 normal term infants over the first year of life.
- DPOAE measurements were taken at 10 f2 primary tone frequencies from 500 Hz to 10 kHz.
- Analysis focused on pass rates and DPOAE levels at different ages (birth, 6 months, 12 months).
Main Results:
- DPOAE pass rates were highest (98.6%) at 6-10 kHz and lowest (22.9%) at 750 Hz in newborns.
- Pass rates remained high (>91%) at 3-10 kHz by 6 months and near 100% by 12 months.
- Low pass rates (<40%) persisted at 750 Hz, with a tendency to decrease at 1 kHz with age.
- DPOAE levels at 4 kHz increased from birth to 6 months, then slightly decreased at 12 months.
Conclusions:
- Most frequencies show no significant age-related changes in DPOAEs or cochlear function during the first year.
- Interpretation of infant DPOAEs must account for age-related pass rate differences at low frequencies.
- High-frequency DPOAE levels also require age-specific interpretation in infants.
Abstract:
Understanding of any age-related differences in distortion product otoacoustic emissions (DPOAEs) during infancy is important for the use of DPOAEs in detection of cochlear impairment in infants. We studied DPOAEs at 10 frequencies of f2 primary tone between 500 Hz to 10 kHz longitudinally during the first year of life in 70 ears of 35 normal term infants. On days 3-5 after birth DPOAE pass rates ranged between the highest 98.6% at f2 frequencies 6-10 kHz and the lowest 22.9% at 750 Hz. The higher the frequency, the higher was the pass rate. At 6 months the pass rates at various frequencies were generally similar to those on days 3-5, and were greater than 91% across the frequencies of 3-10 kHz. At 12 months the pass rates were 100% or near 100% across 3-10 kHz. During the first year the pass rate was always very low at 750 Hz (<40%) and tended to decrease at 1 kHz with the increase in age. DPOAE level at f2 frequencies 4kHz increased from birth to 6 months but then reduced slightly at 12 months. At lower frequencies the age-related DPOAE levels change was less significant. These results indicate that there are no major changes in DPOAE or cochlear function during the first year of life at most frequencies. However, the interpretation of DPOAE results in infants need to take into account the age-related difference in DPOAE pass rate at low-frequency and in DPOAE level at high-frequency.
