Drifting a bit here Jim, but my experience of people who talk loudly through sessions is the other way round: on the whole, in a mixed songs and tunes session, it's the singers who seem to think tunes are background music for them to chinwag to, whereas it's more likely that songs will get listened to.
Sessions in Ireland: I have been to all sorts, including the ones put on for tourists in hotels, and some more genuine pub sessions. Rather odd one in Letterkenny: all the musicians sat in a huddle in the centre of the floor, backs to anyone else around the periphery of the room, never spoke to anyone outside of their huddle, or invited anyone to join in. I did eventually speak to their accordion player to ask the name of a nice tune she had played: I also noted that it was all tunes and no singing: "Oh, our singer isn't here this week", she said. A bit exclusive, or what?
In our local sessions in Scotland, we would always make a point of welcoming any new faces, and inviting them to contribute if they wished to.