Cross-domain processing of musical and vocal emotions in cochlear implant users

Integrating Emotion Perception in Rehabilitation Programs for Cochlear Implant Users: A Call for a More Comprehensive Approach

PURPOSE

Postoperative rehabilitation programs for cochlear implant (CI) recipients primarily emphasize enhancing speech perception. However, effective communication in everyday social interactions necessitates consideration of diverse verbal social cues to facilitate language comprehension. Failure to discern emotional expressions may lead to maladjusted social behavior, underscoring the importance of integrating social cues perception into rehabilitation initiatives to enhance CI users' well-being. After conventional rehabilitation, CI users demonstrate varying levels of emotion perception abilities. This disparity notably impacts young CI users, whose emotion perception deficit can extend to social functioning, encompassing coping strategies and social competence, even when relying on nonauditory cues such as facial expressions. Knowing that emotion perception abilities generally decrease with age, acknowledging emotion perception impairments in aging CI users is crucial, especially since a direct correlation between quality-of-life scores and vocal emotion recognition abilities has been observed in adult CI users. After briefly reviewing the scope of CI rehabilitation programs and summarizing the mounting evidence on CI users' emotion perception deficits and their impact, we will present our recommendations for embedding emotional training as part of enriched and standardized evaluation/rehabilitation programs that can improve CI users' social integration and quality of life.

CONCLUSIONS

Evaluating all aspects, including emotion perception, in CI rehabilitation programs is crucial because it ensures a comprehensive approach that enhances speech comprehension and the emotional dimension of communication, potentially improving CI users' social interaction and overall well-being. The development of emotion perception training holds promises for CI users and individuals grappling with various forms of hearing loss and sensory deficits. Ultimately, adopting such a comprehensive approach has the potential to significantly elevate the overall quality of life for a broad spectrum of patients.

Rapid Assessment of Non-Verbal Auditory Perception in Normal-Hearing Participants and Cochlear Implant Users

In the case of hearing loss, cochlear implants (CI) allow for the restoration of hearing. Despite the advantages of CIs for speech perception, CI users still complain about their poor perception of their auditory environment. Aiming to assess non-verbal auditory perception in CI users, we developed five listening tests. These tests measure pitch change detection, pitch direction identification, pitch short-term memory, auditory stream segregation, and emotional prosody recognition, along with perceived intensity ratings. In order to test the potential benefit of visual cues for pitch processing, the three pitch tests included half of the trials with visual indications to perform the task. We tested 10 normal-hearing (NH) participants with material being presented as original and vocoded sounds, and 10 post-lingually deaf CI users. With the vocoded sounds, the NH participants had reduced scores for the detection of small pitch differences, and reduced emotion recognition and streaming abilities compared to the original sounds. Similarly, the CI users had deficits for small differences in the pitch change detection task and emotion recognition, as well as a decreased streaming capacity. Overall, this assessment allows for the rapid detection of specific patterns of non-verbal auditory perception deficits. The current findings also open new perspectives about how to enhance pitch perception capacities using visual cues.

Musical and vocal emotion perception for cochlear implants users

Cochlear implants can successfully restore hearing in profoundly deaf individuals and enable speech comprehension. However, the acoustic signal provided is severely degraded and, as a result, many important acoustic cues for perceiving emotion in voices and music are unavailable. The deficit of cochlear implant users in auditory emotion processing has been clearly established. Yet, the extent to which this deficit and the specific cues that remain available to cochlear implant users are unknown due to several confounding factors. Here we assessed the recognition of the most basic forms of auditory emotion and aimed to identify which acoustic cues are most relevant to recognize emotions through cochlear implants. To do so, we used stimuli that allowed vocal and musical auditory emotions to be comparatively assessed while controlling for confounding factors. These stimuli were used to evaluate emotion perception in cochlear implant users (Experiment 1) and to investigate emotion perception in natural versus cochlear implant hearing in the same participants with a validated cochlear implant simulation approach (Experiment 2). Our results showed that vocal and musical fear was not accurately recognized by cochlear implant users. Interestingly, both experiments found that timbral acoustic cues (energy and roughness) correlate with participant ratings for both vocal and musical emotion bursts in the cochlear implant simulation condition. This suggests that specific attention should be given to these cues in the design of cochlear implant processors and rehabilitation protocols (especially energy, and roughness). For instance, music-based interventions focused on timbre could improve emotion perception and regulation, and thus improve social functioning, in children with cochlear implants during development.

Neural Processing of Musical and Vocal Emotions Through Cochlear Implants Simulation

Cochlear implants (CIs) partially restore the sense of hearing in the deaf. However, the ability to recognize emotions in speech and music is reduced due to the implant's electrical signal limitations and the patient's altered neural pathways. Electrophysiological correlations of these limitations are not yet well established. Here we aimed to characterize the effect of CIs on auditory emotion processing and, for the first time, directly compare vocal and musical emotion processing through a CI-simulator. We recorded 16 normal hearing participants' electroencephalographic activity while listening to vocal and musical emotional bursts in their original form and in a degraded (CI-simulated) condition. We found prolonged P50 latency and reduced N100-P200 complex amplitude in the CI-simulated condition. This points to a limitation in encoding sound signals processed through CI simulation. When comparing the processing of vocal and musical bursts, we found a delay in latency with the musical bursts compared to the vocal bursts in both conditions (original and CI-simulated). This suggests that despite the cochlear implants' limitations, the auditory cortex can distinguish between vocal and musical stimuli. In addition, it adds to the literature supporting the complexity of musical emotion. Replicating this study with actual CI users might lead to characterizing emotional processing in CI users and could ultimately help develop optimal rehabilitation programs or device processing strategies to improve CI users' quality of life.