IMMITTANCE FINDINGS IN SCHOOL-AGED CHILDREN

Objective: The purpose of the present study was to obtain the median v alues and distributions of tympanometric variables and the distributio ns of acoustic reflex thresholds for three age groups of unselected sc hool-aged children. Furthermore, the investigation was undertaken to p rovide normative immittance data for selected, otologically normal 7-, 10-, and 14-yr-old children. Design: A total of 687 children, aged 6 to 15 yr, were thoroughly examined clinically, audiometrically, and ty mpanometrically. The same examinations were made in 471 otologically n ormal 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. Results: The results showed that the median equivalen t ear canal volume (V-ec) increased from 0.65 ml to 1.00 ml with incre asing age both in the unselected and selected populations. The median peak admittance values (Y-tm) were between 0.55 and 0.5 mmho in the re spective study groups, somewhat higher in older than in younger childr en. The same tendency was also seen in gradient and tympanometric peak pressure (TPP) results. Depending on the age, the median tympanometri c peak pressures were 5 to 10 daPa higher in otologically normal child ren 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 tha n in older children. Conclusions: The obtained results give new inform ation on immittance findings in an unselected sample of school-aged ch ildren 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 e quipment are taken into account.