Take him if it seems to be to loud then leave it maybe sit in the hall where it's not as loud! I'm not sure where ur from n the weather but there will b a lot of petiole there higher chance of him getting sick if there is sick people there, where I live the weather is changing n everyone is sick so I'd keep my new born in but it culd b totally different where u live.
The comment above makes a very good point. Is there someone who could videotape it and you could all watch it later together?
Most times babies that age will get startled really easy, and he will probably cry if it's too loud, if he does I'd definitely take him out and sit in the hall or outside if possible. I probably wouldn't go if it were me, but if it's something you'd really like to be at, you can make it work!