LOL, and without camera you can't move?
Eventhough this is an old question. For people with the same question it is great to see these answers.
Yes, leaving out a part of the performance (voice) affects the whole performance.
Musicians sing along when shooting a musicvideo for that same reason.
Your voice is a tool.
Warm it up, treat it well. Even voice-over actors do this.
Also do an warming up for your jaw, ectually, do it for your whole body: because you need to be ready to act.