Developmental changes in aural acoustic admittance measurements

Tympanometry is a clinical measurement routinely included in the assessment of middle ear function. Despite its widespread use, however, fundamental questions remain regarding the need for age-dependent normative data. This study examines normal developmental changes associated with four tympanometric measurements: (1) ear canal volume, (2) peak compensated acoustic admittance, (3) tympanometric width, and (4) tympanometric peak pressure. Of 221 infants and children, aged 6 months to 5 years, enrolled in this study, 99 met the criteria for normal middle ear function as determined via pneumatic tympanoscopy by an experienced pediatric otolaryngologist, and data analysis was confined to those 99 volunteers. Analysis of variance revealed statistically significant main effects showing increases in ear canal volume and peak compensated acoustic admittance and decreases in tympanometric width as age increased. Statistically significant differences were not achieved for tympanometric peak pressure. Although statistically significant differences were found, the differences were small and of questionable clinical significance.