Medical researchers are breaking sound barriers for children born without a hearing nerve. Hearing loss manifests in various forms, most of which can be partially restored through hearing aids and cochlear implants. Those devices cannot help a small population of individuals who do not have a cochlear, or hearing, nerve -- these people are unable to perceive sound, no matter how loud, outside of feeling vibration. The ABI is considered revolutionary because it stimulates neurons directly at the human brainstem, bypassing the inner ear entirely.