[Characteristic of distortion product otoacoustic emissions for preterm newborn].

OBJECTIVE To investigate the characteristic of distortion product otoacoustic emissions (DPOAE) amplitude, SNR and noise in preterm newborns. METHOD DPAOEs at the 2f1-f2 frequency were recorded from 59 ears of 31 preterm newborns and 35 ears of 19 healthy fullterm newborns in response to equilevel primary tones at postnatal 3 days to 1 week. Detailed test included the recording of DPAOEs, SNR and noise. RESULT The average DPOAE audiogram of preterm newborns illustrating the frequency response of these emissions demonstrated a maximum at 1,587 Hz and a minimum around 4,000 Hz. The DPOAE response amplitude of preterm newborn was lower than that of fullterm in every frequency(P < 0.05). The SNR was higher at 4,000 Hz than that at low frequency, but was lower at 1000 Hz than that at high frequency. At 4,000, 3,175, 1,587, 1,260 and 1,000 Hz, the SNR of preterm were lower thad fullterm(P < 0.05). The noise was higher at low frequency than that at high frequency. CONCLUSION The characteristics of DPOAE in preterm newborn are different from fullterm newborn. These differences may indicate immaturity in cochlear function. Outer hair cell function are hypothesized sources of this immaturity, although some contribution from the immature middle ear and outer ear cannot be ruled out.