Distortion-Product Otoacoustic Emissions (DPEs) in Neonates: Frequency Ratio (F2/F1) and Stimulus Level Differences (L1-L2)

Stimulus parameter values for distortion-product otoacoustic emissions (DPE) recordings in neonates are based on adult studies. The purpose of the present investigation was to determine what values of stimulus frequency ratio (F2/F1) and stimulus level difference (L1-L2) produced the largest DPE amplitude in neonates. Single ear DPE measurements were obtained from 11 preterm neonates (34-36 weeks post-conceptual age) at F2s of 2, 3, and 4 kHz. Ratio sweeps were performed through a frequency range determined by F2/F1=1.4-1.02 at L1-L2s of 0, 5, 10, 15 and 20 dB, where L1=65 dB SPL. The findings indicated that on average, an L1-L2=5 dB and an F2/F1=1.18 produced the largest DPE amplitude across all F2s.