Hearing aids, even the most powerful one, have their limits. Many people, myself included, find themselves either near or past these limits and in the domain of cochlear implants (CI).
Obviously CI are very expensive and require hospitalization and serious surgery to implant. Getting a CI also means that person can no longer have MRI scans performed, a very serious consequence.
Researchers are working with a prototype of a new type of "hearing aid" that is "implanted" in the ear drum, a very minor surgery that is done outpatient. The implant can reach 120 dB, which is fairly amazing. More details on this link: