Functional maturation of the medial efferent olivocochlear system in human neonates.

The effect of contralateral acoustic stimulation on transient evoked otoacoustic emissions (TEOAE) was used to investigate the functional maturity of the medial efferent olivocochlear system in full term neonates and a 6-week-old baby. The technique used was to record the TEOAE alternately with and without contralateral noise. The result was a reduction in TEOAE amplitude and latency. This was best illustrated with a difference waveform obtained from the subtraction of the TEOAE waveform recorded with contralateral noise, from the waveform recorded without contralateral noise. All the full term neonates and also the 6-week-old baby showed significant effects indicating functional maturity of the medial olivocochlear system.