Sorry that you're having this difficulty. It's a difficult problem, a family member has problems with listening to speech broadcasts. There's a weird (for Sony!) product that helped with listening to TV, it is SRS-LSR200 which has analog 3.5 mm and optical inputs to a charging dock, and the speaker is battery-powered so it can be placed close to the listener, and has a "voice zoom" button. It's not bad, I think it is using a very basic DSP though. Nothing configurable. Perhaps that's a possible option. It doesn't have the usual Sony "feel". To me it seems it feels like a cheaply made product, but I didn't find anything else suitable at the time, and it's still in use after 4 years.
By coincidence I have a Yamaha sound bar for my TV, that has the "Clear Voice" button you refer to. To me the sound difference is a subtle change (EDIT: and possibly is volume dependent, the difference seems more prominent if the volume is louder), I can't know for sure if it will help or not, but certainly I do sometimes use it on some TV content that has a lot of annoying music on top of important speech. I've not checked what audio connections it has (I use the optical connection in it I think) but it also has Bluetooth receiver capability built-in.
I could ask a movie sound guy if there's anything he knows about. Different field of course, but maybe there's something real-time to suit this need.
EDIT: If you like, I can record (using a little battery-powered sound recorder) the difference between normal audio and with Clear Voice on the Yamaha device, in case it's the same Clear Voice algorithm as the one on the Yamaha device you're considering. If you have an example recording suggestion, e.g. some song you're very familiar with, then I can play that off Youtube or whatever, through the sound bar, with Clear Voice on and off.