Longitudinal development of wideband reflectance tympanometry in normal and at-risk infants

Abstract

Purpose The goals of this study were to measure normal characteristics of ambient and tympanometric wideband acoustic reflectance, which was parameterized by absorbance and group delay, in newborns cared for in well-baby and Neonatal Intensive Care Unit (NICU) nurseries, and to characterize the normal development of reflectance over the first year after birth in a group of infants with clinically normal hearing status followed longitudinally from birth to one year of age. Methods Infants were recruited from a well-baby and NICU nursery, passed newborn otoacoustic emissions (OAE) and automated auditory brainstem response (ABR) tests as well as follow-up diagnostic ABR and audiometry. They were tested longitudinally for up to one year using a wideband middle ear acoustic test battery consisting of tympanometry and ambient-pressure tests. Results were analyzed for ambient reflectance across frequency and tympanometric reflectance across frequency and pressure. Results Wideband absorbance and group delay showed large effects of age in the first 6 months. Immature absorbance and group delay patterns were apparent in the low frequencies at birth and one month, but changed substantially to a more adult-like pattern by age 6 months for both ambient and tympanometric variables. Area and length of the ear canal estimated acoustically increased up to age 1 year. Effects of race (African American and others compared to Caucasian) were found in combination with age effects. Mean and confidence intervals are provided for use as a normative longitudinal database for newborns and infants up to one year of age, for both well-baby and NICU infants.

Maturation of middle ear transmission in children

“…Overall, these studies demonstrated that the mean absorbance is higher in neonates and young infants up to 6 months of age compared to young adults across the frequency range. Among infants, one-month-old infants showed higher absorbance compared to newborns and older infants (Hunter et al, 2015). The high absorbance in frequencies below 1000 Hz in young infants is conjectured to be due to power loss from flaccid ear canal movement (Keefe et al, 1993).…”

“…Sound transmission through the middle ear undergoes developmental changes throughout infancy (Hunter et al, 2015; Keefe and Levi, 1996; Keefe et al, 1993; Sanford and Feeney, 2008; Werner et al, 2010) and continues into childhood (Beers et al, 2010; Hunter et al, 2008; Okabe et al., 1988; Wang et al, 2016). Maturation of the middle ear transmission has important implications for perceptual and physiologic studies of auditory development.…”

“…Studies that investigated maturational effects in WAI reported ambient energy reflectance, or absorbance, in infants and toddlers of different age groups in cross-sectional (Aithal et al, 2014; Hunter et al, 2008; Keefe et al, 1993; Sanford and Feeney, 2008; Werner et al, 2010) and longitudinal designs (Hunter et al, 2015; Shahnaz et al, 2014). Hunter et al (2015) characterized tympanometric absorbance and reflectance group delay at tympanometric peak pressure, −300 daPa and 200 daPa, in addition to measuring ambient absorbance.…”

“…Hunter et al (2015) characterized tympanometric absorbance and reflectance group delay at tympanometric peak pressure, −300 daPa and 200 daPa, in addition to measuring ambient absorbance. Overall, these studies demonstrated that the mean absorbance is higher in neonates and young infants up to 6 months of age compared to young adults across the frequency range.…”

Wideband Tympanometry

“…Thus, an absorbance test held in nonpressurized conditions will be useful for monitoring middle ear state immediately after surgery, with perforated eardrum during neonatal hearing screening. In several studies performed in ambient pressure proved to be able to detect changes in middle ear function significantly for infants and neonatal measurements [23,24]. In the case of patients with ventilation tubes in the eardrum, data from Groon et al [25], suggest that: (i) for any leak larger than 0.25 mm there are absorbance alteration effects up to 10 kHz; (ii) above 1 kHz these effects are unpredictable; and (iii) absorbance values were mostly increased in the lower frequency bands (0.1-0.2 and 0.2-0.5 kHz).…”