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Probe-tube microphone measurements with very young infants
1Centre for Audiology, Education of the Deaf and Speech Pathology, University of Manchester, UK.
Insights
Probe-tube microphone measurements are feasible and repeatable in unsedated infants. Infant ear resonance frequencies are significantly higher than adults, showing acceptable test-retest stability for clinical use.
Area of Science:
- Audiology
- Pediatric Medicine
- Bioacoustics
Background:
- Accurate ear canal measurements are crucial for infant hearing assessments.
- Previous studies have faced challenges in obtaining reliable data from unsedated infants.
Purpose of the Study:
- To evaluate the feasibility, repeatability, and practicality of probe-tube microphone measurements in unsedated infants.
- To compare external ear resonance frequencies between infants and adults.
Main Methods:
- External ear resonance curves were measured using probe-tube microphones in infants (0-6 months) and adults.
- Test-retest reliability was assessed by repeating measurements after probe-tube repositioning.
- Ear canal volume was estimated using tympanometry.
Main Results:
- Infant mean resonance frequency (4200 Hz) was significantly higher than adult mean resonance frequency (2950 Hz).
- Measurements demonstrated acceptable test-retest stability for resonance frequency and peak size in infants.
- A positive correlation was found between resonance peak size and ear canal volume, but tympanometry was not a reliable predictor of peak size.
Conclusions:
- Probe-tube microphone measurements are practical and repeatable in unsedated infants.
- Infant ear canal acoustics differ significantly from adults, with higher resonance frequencies.
- These findings support the use of probe-tube microphone measurements in pediatric audiology.
Abstract:
The practicalities of performing probe-tube microphone measurements in a clinical environment with unsedated infants were examined. External ear resonance curves (unaided response) were obtained for both ears of a group of infants aged 0-6 months and an adult comparison group. A repeat measure (with probe-tube repositioning) was made to estimate the test-retest reliability of these measures. Results showed that the mean infant resonance frequency (4200 Hz) occurred at a significantly (P less than 0.005) higher frequency than the mean adult resonance frequency (2950 Hz). Infants test-retest differences for resonance frequency (mean = 286 Hz, s.d. = 404 Hz) and size of peak (mean = 2.2 dB, s.d. = 2.6 dB) showed acceptable stability for the measurements. Size of resonance peak was found to vary positively with ear canal volume; however, estimation of ear canal volume from tympanometry did not provide a useful indicator of the size of the peak. The probe-microphone measurements were found to be feasible, repeatable and practical with these infants.