Polyphony--and dissonance--in church

I love plainsong, but I also love polyphony. In fact, almost any form of choral singing. I attend an Episcopal church in Berkeley (St. Mark's), which has for many years enjoyed a choir of some 50 men and women, and it is excellent. There is a regular churchgoer who clearly has some mental problems, although he is in no way dangerous. He does not seem to understand why we sing and pray in unison. He certainly knows the words--and speaks them loudly. He doesn't wait to join in with others, but rushes ahead, a habit which I find quite bothersome. On the other hand, I realize that church is not confined to those who are mentally and physically healthy. Unfortunately for me, another regular, who often sits in the same pew, and thinks that he is word-perfect with the prayers, has the unfortunate habit of adding additional words that don't belong - usually simple words like "and". I find this almost equally disconcerting, as this fellow parishioner also likes to speak very loudly, so I'm constantly hearing his personal version of standard prayers. Then there is the widow of a male Epicopal priest, a retired MD, who has some form of mild dementia, which from time to manifests itself by her returning from the Communion rail and forgetting where she was sitting. I have limited vision and mobility, but I gladly accept these signs of aging in return for (so far!) "having all my marbles". That's thanks to good genes, not to any virtue on my part. I admit to an unfortunate trait: I do think to myself "There but for the grace of God go I". I hereby confess to a lack of compassionate feeling, alas.