[Normative wideband absorbance measures in children: a cross-sectional study]

Objective: This study was to investigate the main characteristics and related factors of wideband absorbance (WBA) in children with normal hearing and to obtain age-specific reference range of WBA. Methods: 384 children between 0-12 years old (615 ears) who visited the Beijing Children's Hospital, Capital Medical University from October 2019 to February 2021 were enrolled, including 230 males (376 ears) and 154 females (239 ears), with totally 306 left ears and 309 right ears. Wideband tympanometry (WBT) was performed and normative WBA data were analyzed by SPSS 24.0 statistical software. Repeated measures and multivariate analysis of variance were applied to the data from 16 points at 1/3-octave frequencies (226, 324, 408, 500, 667, 841, 1 000, 1 297, 1 682, 2 000, 2 670, 3 364, 4 000, 5 339, 6 727 and 8 000 Hz) to evaluate the effects of frequency, age, external auditory canal pressures, gender and ear on WBA. Results: According to the WBT frequency-absorbance curve, the subjects were divided into seven groups: 1-month old group, 2-month old group, 3-month old group, 4-5 month old group, 6-24 month old group,>2-6 year old group and>6-12 year old group. The WBA of normal-hearing children underwent a series of developmental changes with age at both ambient pressure and tympanometric peak pressures. WBA results for 1-month group and 2-month old group exhibited a multipeaked pattern, with the peaks occurring around 2 000 and 4 897 Hz, and a notch around 3 886 Hz. WBA results for 3-month group and 4-5 month old group exhibited a single broad-peaked pattern, with the peak occurring between 2 000-4 757 Hz. The WBA of 1-month old group to 4-5 month old group decreased gradually at low frequency (226-408 Hz) and 6 727 Hz, and increased at middle to high frequency (2 670-4 000 Hz). The WBA of 6-24 month old group were significantly lower than that of 2-month old group to 4-5 month old group at all frequencies except 3 364 and 4 000 Hz. WBA results for 6-24 month old group,>2-6 year old group and>6-12 year old group exhibited a single-peaked pattern, and the peak frequency of WBA moved to the lower frequency successively. From 6-24 month old group to>6-12 year old group, the WBA gradually increased at low to middle frequencies (667-2 670 Hz) and 8 000 Hz, and decreased at middle to high frequencies (3 364-5 339 Hz). Among the 16 frequencies of all age groups, the difference between WBA under ambient pressure and tympanometric peak pressure were -0.09-0.06, and 43.75%-81.25% frequency points had statistically significant difference, which was mainly manifested in that WBA under ambient pressure were lower than that under tympanometric peak pressure at 226-1 682 Hz. There was no significant ear effect on all of the age groups. Similarly, there was no significant gender effect except for 3-month old group and 4-5 month old group. Conclusions: The WBA of normal-hearing children measured at ambient pressure and tympanometric peak pressure varied across the frequencies with age from 1 month to 12 years old, and different frequencies followed different change patterns (increase vs. decrease) in WBA. There was also significant external auditory canal pressures effect on all of the age groups. The establishment of age-specific reference range of WBA for 0-12 years old normal-hearing children in this study would be useful for clinical practice of determining normative data regarding WBT.