A hearing aid is an electroacoustic device which is designed to amplify sound for the wearer, usually with the aim of making speech more intelligible, and to correct impaired hearing as measured by audiometry.
However normal hearing aid can only allow patient to hear a little bit more. Most of them just relies on lip lancet in order to communicate with others.
Miller Reese Hutchinson of New York patented the first portable electric hearing aid. Called the “acousticon,” the device was a smaller version of previous tabletop units. While portable, it still had three components and used batteries that only lasted for a few hours. But it was far superior to ungainly hearing trumpets or simply cupping a hand behind the ear.
The unsolvable problem is to recharge the electric hearing aid after few hours of usage. Therefore, scientists must explore for tiny-but-high-capacity battery so patient who got hearing problem can benefit.
Miller Reese Hutchinson patents first portable electric hearing aid: http://www.news-medical.net/news/20131128/Miller-Reese-Hutchinson-patents-first-portable-electric-hearing-aid.aspx