Distortion product otoacoustic emission suppression tuning and acoustic admittance in human infants: Birth through 6 months

Abstract

Previous work has reported non-adultlike distortion product otoacoustic emission (DPOAE) suppression in human newborns at f 2 =6000 Hz, indicating an immaturity in peripheral auditory function. In this study, DPOAE suppression tuning curves (STCs) were recorded as a measure of cochlear function and acoustic admittance/reflectance (YR) in the ear canal recorded as a measure of middle-ear function, in the same 20 infants at birth and through 6 months of age. DPOAE STCs changed little from birth through 6 months, showing excessively narrow and sharp tuning throughout the test period. In contrast, several middle-ear indices at corresponding frequencies shifted systematically with increasing age, although they also remained non-adultlike at 6 months. Linear correlations were conducted between YR and DPOAE suppression features. Only two correlations out of 76 were significant, and all but three YR variables accounted for <10% of the variance in DPOAE suppression tuning. The strongest correlation was noted between admittance phase at 5700 . The association between middle-ear variables and DPOAE suppression may be stronger during other developmental time periods. Study of older infants and children is needed to fully define postnatal immaturity of human peripheral auditory function.

Auditory Steady-State Evoked Responses for Preterm and Term Neonates

“…Studies on cochlear function, as expressed by the suppression of distortion product otoacoustic emissions, suggest an immaturity in the highfrequency range which may persist to at least the sixth postnatal month [Abdala, 2004]. While it is unclear what may explain the immaturity of postnatal cochlear function, it does not appear to be correlated with acoustic conductance through the middle ear [Abdala et al, 2007]. It is hypothesized that both middle and inner ear immaturity may be responsible for an elevation in hearing thresholds during the infancy period.…”

Maturation of auditory function related to hearing threshold estimations using the auditory brainstem response during infancy

“…Lower conductance of the middle ear of infants for frequencies above 1000 Hz has been reported to prevent such stimuli from reaching the cochlea [37]. Studies on cochlear function following birth have also suggested an immaturity of the cochlea when examining cochlear fine structure using otoacoustic emissions, although it is difficult to parse out cochlear effects to those related to immature acoustic conductance observed in the infant outer and middle ear [38][39][40]. While the immaturity of peripheral structure may be responsible for an elevation of in situ ABR thresholds at certain frequencies, the influence of both effects does not appear to be of sufficient magnitude to completely explain differences observed between infants and adults [18].…”

Maturation and Aging of the Human Cochlea: A View through the DPOAE Looking Glass

“…The value of this approach is in the maintenance of a continuous thread between early and late changes in peripheral function while elucidating patterns unique to each epoch. While distortion product otoacoustic emissions (DPOAEs) have previously been applied as a window into cochlear maturation (e.g., Abdala 1998Abdala , 2000Abdala et al 2007) and, to a lesser extent, aging (e.g., Lonsbury-Martin et al 1991;Dorn et al 1998), the present study included an age continuum spanning nearly eight decades, considered current OAE generation theory and evaluated independent changes in magnitude and phase of dual DPOAE components.…”