I posted in the Tim Eriksen thread about the shape note singers at the
newport folk festival in 2006. Tim_Eriksen_And_The_Shape_Note_Singers on mvy radio
check this out...from martha's vineyard radio archives.

the group singing starts about 6 minutes into the clip.
As Tim states, this is a 200 year old community singing tradition.
not usually seen as a performance, but as an group involvement
tradition.

Fa so la!