Good on you for gathering info re this particular curiosity! It’s important.
Suggestion: Google has a search feature called Google Scholar. Using it, I found some useful studies re your subject of interest by using combinations of the following search terms–choral group singing, social group cohesion, sense of community.
You might also use search terms like choral music (or choral singing) and empathy
If I find some juicy ones I’ll send them to you.
If you would be willing to email me an email address, I could send you a few full-length articles, etc., that may be helpful to you. My email address is firstname.lastname@example.org