title: Longitudinal development of wideband reflectance tympanometry in normal and at-risk infants.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: Cincinnati Children's Hospital Medical Center, USA. Electronic address: lisa.hunter@cchmc.org.
authors.forename: Lisa L
authors.initials: LL
authors.lastname: Hunter
authors.affiliation: Boys Town National Research Hospital, USA.
authors.forename: Douglas H
authors.initials: DH
authors.lastname: Keefe
authors.affiliation: National Center for Rehabilitative Auditory Research, USA; Oregon Health & Science University, USA.
authors.forename: M Patrick
authors.initials: MP
authors.lastname: Feeney
authors.affiliation: Boys Town National Research Hospital, USA.
authors.forename: Denis F
authors.initials: DF
authors.lastname: Fitzpatrick
authors.affiliation: Cincinnati Children's Hospital Medical Center, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Lin
mesh_terms: D000158:Acoustic Impedance Tests / Q000379:methods*; D000161:Acoustic Stimulation / Q000379:methods; D001300:Audiometry, Evoked Response / Q000379:methods*; D004424:Ear Canal / Q000502:physiology; D004432:Ear, Middle / Q000502:physiology*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D015997:Neonatal Screening / Q000379:methods*; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D012016:Reference Values
keywords: Development; Middle ear; Newborn screening; Reflectance; Tympanometry