Bilateral cochlear implants in children: binaural unmasking.
Bilateral cochlear implants (CIs) may offer deaf children a range of advantages compared to unilateral CIs. However, speech perception in noise is mainly facilitated by better-ear effects and much less by interaural comparisons or true 'binaural' hearing. Little is known about the development of the binaural auditory system with CIs provided at a young age. It is possible that, as with adults, binaural sensitivity exists but is not accessed due to technical limitations in electrical stimulation methods. In this paper, we present results on binaural hearing in children with bilateral CIs. Binaural masking level differences (BMLDs) were measured for a 180-degree phase shift in a 125-Hz sinusoid, presented in a 50-Hz-wide noise band and modulating a 1000-pps carrier pulse train. Stimuli were presented to a single electrode in the middle of the electrode array at both ears. Eight children between 6 and 15 years of age participated in this study. Six children had a significantly better detection threshold when the signal was out of phase (dichotic) between two ears than when it was in phase (diotic), with a mean difference (BMLD) of 6.4 dB. The present results show that children with bilateral CIs are sensitive to binaural cues in electrical stimuli, similar to adults, even when implants are provided at a later age and with a longer delay between implantations.
Van Deun
Lieselot
L
ExpORL, Department of Neurosciences, KU Leuven, Belgium. lieselot.vandeun@med.kuleuven.be
van Wieringen
Astrid
A
Francart
Tom
T
Scherf
Fanny
F
Dhooge
Ingeborg J
IJ
Deggouj
Naïma
N
Desloovere
Christian
C
Van de Heyning
Paul H
PH
Offeciers
F Erwin
FE
De Raeve
Leo
L
Wouters
Jan
J
D000293:Adolescent; D001307:Auditory Perception / Q000502:physiology; D001309:Auditory Threshold; D002648:Child; D003054:Cochlear Implants; D003638:Deafness / Q000151:congenital / Q000503:physiopathology* / Q000628:therapy*; D004007:Dichotic Listening Tests; D004558:Electric Stimulation; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D010470:Perceptual Masking / Q000502:physiology*; D011571:Psychoacoustics; D013017:Sound Localization / Q000502:physiology