Voices, sounds, and music really should be left to the end of the production -- it's one of those things that has to be done very, very carefully as it can utterly destroy the atmosphere of a game if rushed.
With regards to voice actors -- just don't, unless you can afford some top-tier talent; trying to find cheap actors who can pull-off the voices you have in your head for your characters is a waste of energy, and as many of us have been around since the start of this game, we all have given these characters our own voices, so having 'new' voices turn up will feel off (don't know why, but the Macy in my head sounds like she's from Brooklyn, and if she suddenly starts speaking with a strong British accent, it'd be kinda jarring).
IMHO
naughtyroad are doing just fine and should keep what they're doing. If at the end of the production there are enough funds to hire a sound designer, then give the project sound, but as I
almost always turn the sound down on these types of games (and I am in no way unique), why waste time and money on sound?