The World Health Organization estimates that around 466 million people suffer from disabling hearing loss, with children constituting 7% of this population (2019). While cochlear implants aren’t suitable for all hearing-impaired individuals, sensory substitution principles, like non-invasive vibrotactile techniques, can be used to assist hearing-impaired patients.
Our study aimed to prove systematically, that sensory-substitution-based acoustic perception via spinal cord stimulation (SCS) could mimic cochlear implant functionality in hearing adults.
Personalized SCS settings were calibrated for nine recently implanted patients to induce distinct sensations. These sensations were then used in pattern discrimination tasks. Sound samples, such as voices and warning sounds, were translated into stimulation patterns with fixed durations and volumes. Patients were presented with groups of four sound examples in a forced-choice design, requiring them to discern them based solely on the sensations felt. Sets included one confusion pair with similar patterns, enabling advanced testing (e.g., distinguishing a fire alarm from a car siren).
We achieved computer-to-brain communication in 7 out of 9 patients within a 10-minute learning phase. Of these, 6 could distinguish sound samples above chance level, with an overall mean performance of 70%. Individual performance ranged from 42% to 87%, with the chance level set at 1/3.
Our study demonstrates the potential of sensory-substitution-based acoustic perception via spinal cord stimulation as a promising approach for hearing-impaired individuals. This proof of concept opens avenues for interventions aiming to enhance auditory perception and improve quality of life for those unsuitable for traditional cochlear implants. Further research should refine sound-encoding and signal-transferring methods while expanding sample size and patient diversity to validate the generalizability of our findings.
Funding: CereGate GmbH.
