Distortion Product and Spontaneous Otoacoustic Emissions in Normal Neonates

Chang, Sun O; Oh, Seung Jun; Koo, Ja Won; Lim, Dukhwan; Hwang, Chan Ho; Kim, Chong Sun; Choi, Joong Hwan

Abstract

BACKGROUND AND OBJECTIVES: Distortion product otoacoustic emission (DPOAE) offers an alternative to transiently evoked OAE as a neonatal hearing screening, and may provide frequency specific information of the cochlea. The purpose of this study is to establish the relevant characteristics of spontaneous OAE (SOAE) and DPOAE of neonates and their efficacy as a neonatal screening method for hearing loss.
MATERIALS AND METHODS
From July to September 1999, 72 healthy newborns (144 ear) were included in this study and test was performed within 3 days after birth at nursery. DP audiogram, input/output (I/O) curve at 3 kHz, and SOAE were recorded.
RESULTS
The DP audiogram had characteristics with two broad peaks of amplitude at Fe (geometric mean of two primaries) frequencies of 3 kHz and 6 kHz. From the Fe near 3 and 6 kHz, DPOAE was found over 95% of 144 ears. Median threshold of 3 kHz I/O curve was 40 dB. The threshold in 3 kHz could be obtained even in 7 ears that had failed to pass DP audiogram. The thresholds of the ears that failed in DP audiogram were not statistically different from those that passed the test, The amplitude in DP audiogram was not correlated with the threshold in 3 kHz I/O curve. The positive rate for SOAE was 45% (39% in male, 53% in female, 51% in right ear, 38% in left ear, respectively), All the SOAE positive cases passed DP audiogram test.
CONCLUSIONS
DPOAE has a potential for neonatal screening test for hearing loss. Near 3 kHz and 6 kHz, DPOAE were highly positive, and these frequencies can be used in screening test. The duration of a diagnostic test would be shorter by excluding certain frequencies. Using the 3 kHz I/O curve in addition to DP audiogram may increase the validity and the e6cacy of the test. SOAF has limitations as a single modality of neonatal screening test for hearing loss.