Distortion Product Otoacoustic Emissions (DPOAE) can be used as an alternative to Transient Evoked Otoacoustic Emissions (TEOAE). This study aims to establish normal values for DPOAE in healthy newborns. DPOAE were determined with the Madsen Celesta 503 at 0.5, 1, 2, 4 and 8 kHz with an unequal stimulus level of the primaries (L1 = 65 dB SPL, L2 = 50 dB SPL). DPOAE were present in 92.4% of the ears of the 185 babies tested at 4 days after birth. The 5% quantile and the median of the DPOAE of the right and left ears were calculated for the five frequencies tested. At 4 kHz there was a significant sex effect (mean amplitude of DPOAE was higher in female than in male babies) and at 2 kHz a significant interaction effect was found between sex and side. The calculated reference limits are open to comparison with data obtained using other commercial equipment.
The aim of this study was to evaluate distortion product oto-acoustic emissions (DPOAEs) as a means of objective audiometry in a population of children with ventilation tubes. We measured DPOAEs at two different stimulus levels--recorded transient evoked oto-acoustic emissions (TEOAEs) and obtained pure-tone audiometry (PTA). DPOAEs were compared with the normal range proposed by the Madsen company: the CELESTA 503 provides a 'normalized' distortion-product-gram which we compared with the pure-tone threshold of the test group. DPOAEs at 60 dBSPL were more easily obtained in the test group than TEOAEs and PTA. Correlation between 'normalized' DPOAEs and pure-tone thresholds was the strongest at 2 and 4 kHz. Surprisingly, DPOAEs at 60 dBSPL showed significant differences also at 2 and 4 kHz compared with the Madsen data. DPOAEs at 60 dBSPL might be an easy, objective test for evaluating auditory function and for determining hearing threshold at 2 and 4 kHz.
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