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Low-Intensity Distortion Product Otoacoustic Emission Protocols in Infants and Young Children: Contributions of
Ana Paula Bruner1, Uzma Shaheen Akhtar2, Sumitrajit Dhar3
1Faculdade de Medicina da Universidade de São Paulo (FMUSP), Brazil.
Insights
Outer and middle ear characteristics influence distortion product otoacoustic emissions (DPOAEs) in children. Age-specific normative data are crucial for accurate interpretation of DPOAEs, especially with reduced stimulus intensities.
Area of Science:
- Audiology
- Pediatric audiology
- Otoacoustic emissions
Background:
- Cochlear maturity is nearly complete at birth, yet distortion product otoacoustic emission (DPOAE) levels differ between neonates/infants and older individuals.
- These differences suggest functional immaturity in the cochlea and potential roles of the outer and/or middle ear.
- Wideband tympanometry (WBT) provides insights into outer and middle ear function.
Purpose of the Study:
- To investigate the relationship between outer and middle ear characteristics measured by WBT and DPOAEs in children aged 6 days to 5 years.
- To evaluate the applicability of normative criteria for DPOAEs at reduced stimulus intensities in this pediatric population.
Main Methods:
- 109 ears from 60 participants (newborns, 6-8 month olds, 3-5 year olds) were analyzed.
- Measurements included ear canal volume, acoustic admittance (1-kHz and 226-Hz probe tones), acoustic absorbance, and DPOAEs.
- DPOAEs were recorded using two stimulus intensity protocols (L1-L2 = 65-55 dB SPL and 55-45 dB SPL); statistical analyses used nonparametric tests and correlation models.
Main Results:
- Wideband tympanometry measures indicated age-related maturation of the conductive pathway.
- Acoustic absorbance, DPOAE levels, and signal-to-noise ratios (SNRs) were significantly higher in neonates and infants compared to older children, particularly at high frequencies.
- Reduced stimulus intensities (55-45 dB SPL) resulted in lower DPOAE amplitudes and more absent responses across all age groups, though SNRs generally remained above 6 dB.
Conclusions:
- Structural characteristics of the outer and middle ears influence sound transmission, affecting DPOAE detectability.
- Reduced stimulus intensities impact DPOAE measures differently across age groups.
- Implementing age-specific normative data is recommended for improved accuracy in interpreting pediatric DPOAE results.
Purpose:
Despite almost complete cochlear maturity at birth, distortion product otoacoustic emission (DPOAE) levels in neonates and infants are typically higher than those measured in older children and adults, depending on the type and frequency stimulus, which suggests functional immaturity of the cochlea as well as the role of the outer and/or middle ear. This study aimed to investigate the relationship between outer and middle ear characteristics, using wideband tympanometry (WBT), and DPOAEs and to evaluate the applicability of normative criteria at reduced stimulus intensities in children aged between 6 days and 5 years.
Method:
A total of 109 ears from 60 participants were examined and categorized into three age groups: newborns, infants (6-8 months), and children (3-5 years). The following measurements were analyzed: ear canal volume, compensated acoustic admittance (with 1-kHz probe tone and 226-Hz probe tone), acoustic absorbance, and DPOAEs with two stimulus intensity protocols (L1-L2 = 65-55 and 55-45 dB SPL). Statistical analyses included nonparametric tests and correlation models.
Results:
WBT measures reflect the age-related maturation of the conductive pathway. Absorbance, DPOAE response levels, and signal-to-noise ratios (SNRs) were higher in neonates and 6- to 8-month-olds than in the 3- to 5-year group, especially at high frequencies. Lower stimulus levels (L1-L2 = 55-45 dB SPL) led to reduced DPOAE amplitudes and increased rates of absent responses across all groups, although the SNR remained above 6 dB in most ears.
Conclusions:
The findings suggest that the structural characteristics of the outer and middle ears alter both the forward and reverse sound transmission properties, impacting DPOAE detectability. Reducing stimulus intensities affected DPOAE measures differently across age groups; however, the use of age-specific normative data may improve the accuracy of result interpretation.
