Bilateral cochlear implants in children: binaural unmasking

Area of Science:

• Auditory Neuroscience
• Biomedical Engineering
• Pediatric Audiology

Background:

• Bilateral cochlear implants (CIs) offer potential advantages over unilateral CIs for deaf children.
• The development of binaural hearing with CIs in children is not well understood.
• Current electrical stimulation methods may limit the access to binaural sensitivity.

Purpose of the Study:

• To investigate binaural hearing abilities in children with bilateral CIs.
• To assess sensitivity to binaural cues in electrical stimulation.
• To compare binaural hearing in children with findings in adults.

Main Methods:

• Measured binaural masking level differences (BMLDs) using a 180-degree phase shift.
• Stimuli included a 125-Hz sinusoid in a 50-Hz noise band, modulating a 1000-pps carrier pulse train.
• Tests were conducted on eight children (6-15 years) with bilateral CIs, presenting stimuli to single electrodes in both ears.

Main Results:

• Six out of eight children showed significantly better detection thresholds for out-of-phase (dichotic) signals compared to in-phase (diotic) signals.
• A mean binaural masking level difference (BMLD) of 6.4 dB was observed.
• Children demonstrated sensitivity to binaural cues in electrical stimuli.

Conclusions:

• Children with bilateral CIs exhibit sensitivity to binaural cues, comparable to adults.
• This sensitivity can be present even with later implantation and delays between devices.
• Findings suggest potential for improved binaural processing with bilateral cochlear implantation in children.