In recent decades, there was a great expansion for bilateral cochlear implantation (bCI) in children, leading to an improvement of their quality of life. However, spatial hearing skills of bCI children remain limited, even for children with the best speech understanding outcomes. Recent studies have brought new insights in spatial hearing by using virtual reality to record spatial hearing performance in 3D and the impact of active listening (i.e. free head exploration during sound emission): all bCI children showed spatial hearing difficulties related to front-back confusions and distance perception, which partly resulted from the reduction in auditory cues by the CI settings. However, bCI children notably improved under conditions of active listening, suggesting that interaction with environment could represent a rehabilitation entry strategy to help bCI users when faced with complex auditory scenes in daily life.

The ability to localize sounds in space (spatial hearing) and the ability to understand speech in noise are both auditory skills essential in daily interactions with our physical and social environment and, when deficient, limit the quality of life. However, there is no specific rehabilitation program devoted to spatial hearing which could help children face their daily difficulties in noisy environments. Even though technological advances are crucial to improve the restoration of hearing functions, these improvements are also highly dependent on rehabilitation strategies to train our auditory brain to face the restoration of binaural processing or to decode the impoverished spectral information delivered by the CI.

The investigators recently performed a pilot study in bCI adults who attended 8 training sessions of spatial hearing, involving a sensorial and interactive immersive environment (i.e. virtual reality with auditory and visual environment during an active listening task). All participants benefitted of the training, in terms of spatial hearing performance, speech understanding in noise, and quality of life. All early benefits were maintained 1 month after the end of training.

The investigators aim to propose a spatial hearing rehabilitation program (KidTrain) adapted to bCI children from 8 to 17 years old, based on their previous pilot study on bCI adults. Their tool makes it possible to propose rehabilitation programs adapted to the performance and expectations of each child. This program will manipulate both the ambient sound with varying background noise to simulate daily life environments (i.e. making auditory detection more or less complex), and also manipulate virtual immersive environment (i.e. giving more or less relevant visual cues related to real sound location). The KidTrain's effects will be measured with different auditory tests performed in noisy environments. The investigators will also include Normal Hearing (NH) children as age-matched control groups to perform the auditory tests in noise. These NH groups will also bring new insights of spatial hearing maturation in complex auditory environments. Based on our preliminary data in bCI adults, this 'KidTrain program' should improve spatial hearing skills of bCI children, speech comprehension in noise and quality of life in many daily situations.

Virtual reality (VR) has recently proven its effectiveness in rehabilitation in many domains and recent studies have shown that this technology has its place in the auditory evaluation and adaptation of spatial hearing. This VR approach takes advantage of the control of multisensory cues of our environment (audio and visual) during a spatial hearing task, and allows the subject to interact with his environment according to his hearing abilities and needs (i.e. active listening).

Based on their previous study conducted in bCI and NH children and on their spatial training study conducted with bCI adults, the investigators wish to respond to the growing need of spatial hearing rehabilitation for bCI children. To achieve this goal, the investigators will improve the spatial training program by adding different immersive environment in VR with various background noise to simulate daily life environments. This approach will also be a great opportunity to characterize the developmental stages of spatial hearing maturation in NH children. Thus, this project will propose new axes of speech therapy on the Orthophonie & Surdité platform, combining spatial hearing and speech understanding in noise. This innovative and adapted rehabilitation program will lead the speech therapist to propose more adapted and effective rehabilitations for the daily life of deaf children.

Inclusion Criteria:

• Child aged between 7 and 17 years
• Normal vision (including correction),
• Able to understand the experimental instructions,
• Parents or guardians informed of the study and having signed the consent form,

Specific for NH:

• Normal tone audiometry (mean threshold ≤ 30 dB). Specific for bIC
• Minimum 2 years of binaural experience,
• Average speech recognition ≥ 80% with both cochlear implants

Exclusion Criteria:

• Bilateral vestibular areflexia,
• Attention deficit disorder,
• Known neurological or psychiatric disorders,
• Oculomotor disorders,
• Parents not affiliated to a social security scheme or beneficiaries of a similar scheme who sign the consent for the child's participation,
• Subject participating in other interventional research with an exclusion period still ongoing at inclusion.