Objectives: In infants, auditory tests are mainly performed during sleep, s
ince they spend most of their time asleep, and because quiet is required fo
r the duration of the recording session to obtain a precise and reliable re
sponse. The aim of this study was to investigate the effect of sleep stages
on synchronized spontaneous otoacoustic emissions (sSOAEs) in pre-term neo
nates at the age where the sleep states begin to be well established and au
ditory screening can be performed in a neonatalogy unit before discharge.
Methods: Synchronized SOAEs were repeatedly recorded during a polygraphic s
leep recording using the Otodynamic ILO88 system in 10 pre-term neonates at
36 weeks post-conception.
Results: Variations of sSOAE peak numbers occurred in each subject during t
he recording session. There was no clear relation between sSOAE peak number
fluctuations and the different sleep stages.
Conclusions: The sSOAE variations appeared to be closely related to experim
ental conditions, i.e. the mean background noise level. sSOAEs with the hig
hest amplitude were always recorded; however, those with the smallest ampli
tude were the first to disappear from the recordings with higher background
noise. (C) 2000 Elsevier Science Inland Ltd. All rights reserved.