Distortion-product otoacoustic emission growth curves in neonates
Tania Alves Barbosa1, Alessandra Spada Durante1, Lidio Granato2
1Faculty of Medical Sciences, Santa Casa de São Paulo, São Paulo, SP, Brazil.
Background:
The recording of otoacoustic emissions (OAE) enabled us to prove that the cochlea is able not only to receive sounds but also to produce acoustic energy. Through the use of distortion-product otoacoustic emission measurements, the growth of the response was seen according to the intensity of the sound stimulus presented (growth curve).
Objective:
to determine the thresholds for the emergence of distortion-product otoacoustic emissions (DPOAE) on frequencies of 2000 and 4000 Hz with a stimulus varying from 20 to 65 dB SPL, and to establish the slope values obtained in the growth curves.
Methods:
39 neonates aged 5 to 28 days without risk indicators of hearing loss were studied. The DPOAE growth curves were obtained on the frequencies from 2000 Hz and 4000 Hz with a level of intensity ranging from 20 to 65 dB SPL divided into two paradigms (20 to 40 dB SPL and 40-65 dB SPL).
Results:
there was a statistically significant difference in the thresholds for the emergence of DPOAE depending on the criteria used. The thresholds were on average higher at 4000 Hz than 2000 Hz and the slope was higher on average at 2000 Hz than 4000 Hz, although not statistically significant in either case.
Conclusion:
the thresholds were on average 30 dB SPL at 2000 Hz and 35 dB SPL at 4000 Hz. The slope values varied between 3 and 4 on average, reaching 15 in some cases.
