Summary of: Hunter, L. L., Keefe, D. H., Feeney, M. P., Fitzpatrick, D. F., & Lin, L. (2016). Longitudinal development of wideband reflectance tympanometry in normal and at-risk infants. Hearing research, 340, 3–14. https://doi.org/10.1016/j.heares.2015.12.014
Absorbance is a tool which can be used to identify middle ear pathology in infants. It can be measured at tympanic peak pressure or at ambient pressure. This study looked to measure the absorbance characteristics of the middle ear at both ambient and tympanic peak pressure in a group of healthy newborns over a 1-year period. In-line with previous studies looking at absorbance in newborns, the result showed large age effects during the first 6 months of life. As a consequence, the authors recommend that age specific normative data is available up until this time. Between 6 – 15 months these changes are much smaller and thus only a single set of normative data is required. Interestingly, measurements recorded at peak tympanic pressure and at ambient pressure differed at all age groups. These differences were particularly noticeable in newborns. Here, the authors suspect this is a result of the pressurized condition opening the ear canal when the pressure sweep is run from positive to negative pressure, or closing the ear canal walls if run from negative to positive pressure. The authors note that access to age appropriate normative data based on the method used to measure absorbance is essential.