Most 5.1 audio sources favor the center channel heavily for voices, so if you have a stereo soundbar, or one with a weak center channel, you'll need to boost that channel considerably, relative to the rest, then increase overall volume.
If the EQ/mixers available can't achieve acceptable results, get something that has a decent center channel. Ideally this would be a discrete center speaker, but if space is an issue, there are '3.0' or '5.1' soundbars that should suffice.
If the EQ/mixers available can't achieve acceptable results, get something that has a decent center channel. Ideally this would be a discrete center speaker, but if space is an issue, there are '3.0' or '5.1' soundbars that should suffice.