Animate dead command communication. How does it work?

Question

Animate Dead creates minions that can be made to attack, and move.

Is this via talking, a free action? And therefore subject to the limitations of speech, which could be countered with something like Zone of Silence?

Or this more "force of will", making it harder to subvert?

Strictly by the official rules in this case.

Answer 1

The first line of the spell description reads (emphasis mine):

This spell turns corpses into undead skeletons or zombies that obey your spoken commands.

There is nothing in the Paizo FAQ to countermand this, so your answer seems pretty clear.