High-resolution prosthetic hearing with a soft auditory brainstem implant in macaques

Individuals with compromised cochlear nerves are ineligible for cochlear implants and instead rely on auditory brainstem implants (ABIs). Most users of ABIs experience sound awareness, which aids in lip reading, yet not speech intelligibility. Here we engineered a dual-site (brainstem and cortex) implantable system, scaled to macaque anatomy, for the analysis of auditory perception evoked by electrical stimulation of the cochlear nucleus. A soft multichannel ABI, fabricated using thin-film processing, provided high-resolution auditory percepts, with spatially distinct stimulation sites eliciting cortical responses akin to frequency-specific tuning. Behavioural responses collected over several months were sufficiently precise to distinguish stimulations from adjacent channels. Soft multichannel ABIs may aid the rehabilitation of individuals with profound hearing loss who are ineligible for cochlear implants.