The Effect of Body Position on Distortion Product Otoacoustic Emissions Testing in Neonates

Abstract

The current study investigated the effects of body position on the measurement of distortion product otoacoustic emissions (DPOAEs) in newborns. DPOAE measurements are commonly used to screen for hearing loss in newborn hearing screening programs conducted in hospitals nationwide. To measure DPOAEs, a small probe is placed in the external ear canal and a series of tone pairs is presented to the ear. The ear's acoustic response to these tones is measured to determine if the infant is at risk for a hearing loss. Research in adults has indicated effects of body position on DPOAE levels and noise floor levels (Driscoll et al., 2004). However, no information is available on the effects of body position on DPOAE testing in infants, despite the fact that newborn screening is one of the primary clinical applications of DPOAEs. Participants were 47 full-term newborns recruited from the well-baby nursery. DPOAEs were measured from the right ear while the infants were in each of three body positions: lying on the left side, supine, and head raised 45 degrees from supine. DPOAE levels, noise floor levels, DPOAE/noise levels, test time, and pass/fail rate were compared across body positions to determine whether there is an optimal body position for newborn hearing screenings that would minimize test time and/or increase specificity. No statistically significant differences were found in the various DPOAE measures or screening results across body positions or between genders. Significant effects of frequency on DPOAE levels and noise floor levels were similar to those expected based on the literature (e.g., Gorga et al., 1993). The results suggest that newborn hearing screenings on infants in the well-baby nursery can be conducted in different body positions without significantly influencing the screening outcome or measurements obtained.