Play the game as normal, but don't go inside the Church of Martel in Palmacosta yet. After Colette loses her voice, go back to Palmacosta as soon as possible. Talk with the preacher, and Colette should just give a random series of "..." like she's supposed to. Now when you walk out, Colette will be talking about the imposters, even though she is "mute."
Submitted by: Thor