There is a short video on this by Dr. Ben Miles that explains this really succinctly and with visuals.

https://youtube.com/shorts/O8HZw4AbttQ?si=QSCjyDGEIr3Ll-5h

My short interpretation is that you basically inject a virus to mutate cells permanently and it regrows missing hair that takes sound waves and turns them into electrical impulses in the brain.

Absolutely amazing!