I have not found something about this but suspect it is a common problem and I just do not know how to search.
At many venues, not as much formal concerts but sessions, coffee houses, festivals and pubs, when there are a number of us who have come particularly to hear the music, it seems that often the wives, girlfriends (I listen to far more men than women), good buddies, long-term fans and such seem to be the biggest offenders in making so much noise it is hard to hear. I can understand (sort of) how this happens, when they get to hear the musician so often it is not a novelty to them but they may not see each other as often, but I have not run across any way that works to limit it. I have not been impressed with the 'shush' having any effect. Aside from places in which there is someone whose job is (and is known to be) keeping order, who can say, 'please, people would like to listen' or 'perhaps it would be easier to converse in the courtyard' (a line I admired from a doorkeeper in New Orleans), it seems harder than random strangers making noise, and the musician is rather at a disadvantage at least while the performance is going on. Anyone have any suggestions?