I just wondered if the playable character(s) are voiced or silent.

They're voiced when they make comments and such. See this old KS video for more info.

Thank you.

There are several voice options for male and female characters and their voiceovers are limited to short lines spoken in the midst of other activity. Full dialogues are text-only. Recruitable NPCs work similarly, save that you don't get to choose a voice for them.