I recognize this annoyance you have and would say just that everything else that comes up during the retreat (annoying person next to you coughing all the time

I recognize this annoyance you have and would say just that everything else that comes up during the retreat (annoying person next to you coughing all the time etc) is part of the exercise. Observe and accept your reaction and keep on practicing. It is all part of the process. This does not mean that you have to accept all the contents of the discourse as truth or correct or agree. You are listening and meditating, use it as practice. And no one's going to bust you for not participating in chanting.