What constitutes a choir for various pre-novus ordo monastic rites?

I was "assisting" (more like just attending) some Latin vespers, Mass and other hours at a Benedictine Monastery last week and I raised this question with a friend of mine but he didn't know the answer because he'd never been to this monastery, although he had been in formation to be a monk for several years. Are the people on the other side of the fence considered something besides the choir at these liturgical functions? All I'm really familiar with is the TLM sung high Mass and the very quiet low Mass (with a few variations in between). So I'm not used to attending something where we don't even mutter "_et cum spiritu tuo_". Also, there seemed to be a second choir of five or six monks who gathered together in the middle (Between the three rows of monks in the middle) and they seemed to have some extra function, maybe they sang or responded more. I couldn't quite tell what was going on, but were _they_ the choir or were all the monks the choir, or were we all the choir and just didn't say anything?