The organizer of the venue/club/session has to have a previous agreement with the management that what you are trying to do is create a "listening" environment. Set your rules and be very firm in enforcing them. Explain to the people making noise that it is a "listening room". If they persist, tell them that they have the choice to leave, go to another part of the establishment or shut up. If they won't be quiet ask the management to cut them off. If they paid to get in, give them their money back (don't quibble)and have them shown out. Don't get yourself in trouble, have the managment call the police. Even if it is a freebie to get in, if you can establish a "Listening Room" where a lot of people come in, the management will support you if there is money coming in, especially on the Sunday thru Wedneday "off nights".