Immittance findings in school-aged children

The purpose of the present study was to obtain the median values and distributions of tympanometric variables and the distributions of acoustic reflex thresholds for three age groups of unselected school-aged children. Furthermore, the investigation was undertaken to provide normative immittance data for selected, otologically normal 7-, 10-, and 14-yr-old children.

A total of 687 children, aged 6 to 15 yr, were thoroughly examined clinically, audiometrically, and tympanometrically. The same examinations were made in 471 otologically normal children, selected from the total population on the basis of the findings that both tympanic membranes were otomicroscopically healthy, and the hearing thresholds were better than or equal to 25 dB HL at all frequencies.

The results showed that the median equivalent ear canal volume (Vec) increased from 0.65 ml to 1.00 ml with increasing age both in the unselected and selected populations. The median peak admittance values (Ytm) were between 0.55 and 0.5 mmho in the respective study groups, somewhat higher in older than in younger children. The same tendency was also seen in gradient and tympanometric peak pressure (TPP) results. Depending on the age, the median tympanometric peak pressures were 5 to 10 daPa higher in otologically normal children than in the unselected population. The median TPP was -10 daPa in a group of unselected children, and -5 daPa in a group of otologically normal children. The distribution of ipsi- and contralateral acoustic reflex thresholds is presented. Thresholds were higher in younger than in older children.

The obtained results give new information on immittance findings in an unselected sample of school-aged children who were representative of children in the general population. Furthermore, the results are useful as normative immittance values in 7-, 10-, and 14-yr-old children when the limitations relating to the equipment are taken into account.