Normative values for tympanometry in 7- and 24-month-old children.

The objective was to determine normative values for tympanometric variables for 7- and 24-month-old children and to assess the effect of various factors on these variables. Tympanometry was performed at scheduled health visits at 7 and 24 months of age on children recruited to a prospective vaccine efficacy trial (n=2497 children at enrolment). Tympanograms obtained successfully from healthy ears with no recent otitis media were analysed. Normative values for static acoustic admittance (SAA), tympanometric peak pressure (TPP) and tympanometric width (TW) were calculated. The mean SAA was 0.25 cm3 at the 7-month visit compared to 0.34 cm3 at the 24-month visit. The TW decreased and TPP remained unchanged with age. Higher SAA values were found in boys. A history of recurrent acute otitis media and history of tympanostomy tubes were found to increase SAA and decrease TW at 24 months. In conclusion, age-specific normative values for interpretation of SAA and TW are necessary.