Voice changing

[GilesTheCleric]

I don't use any such stuff, but I do think it's possible to find little tricks and techniques that can do the job for you.
When two NPCs are speaking to each other, look to your right when you're A and to your left when you're B, for example. When they're speaking to the PCs, you can have one knit his brows while the other smirks, for example.
And as for doing voices, practice makes perfect. You'll feel silly practicing by yourself at first, but once you get past that it really lifts your performance.

I'll give practicing a try, certainly. I've heard that changing your facial expression changes how your voice sounds -- is this true in your experience? So even without video, making faces might help?

I wold suggest having a few different hats, each representing various NPCs.

I do own many hats, but unfortunately we don't use video when we're playing (two reasons -- we can't see people and the gameboard at the same time, and video crashes my computer). A good suggestion, though!