Since bad hearing is involved, you need to look at soundbars that address those issues specifically.

The most popular of these is the ZVOX soundbars. They sound like crap to anyone with normal hearing. But the few that I have installed, the customer (with hearing problems) love them. And say they sound great to them, because they can actually hear the words now.

They seem to have a good price on their AV357 right now. For $135, free shipping, and 60 day return window - can't hurt to try it.
[Link: zvox.com]