How do I encourage fellow riders not to yell in residential areas early in the morning?
If it is a club or organized ride contact the organizer and let him/her know the problem.  Usually there will be a communication mechanism that they can use to inform riders of the problem and corrective action. If no action is taken, and it is a huge problem, you can go one level up to the sponsors or a higher governing body (clubs are usually members of a larger cycling associations).  Usually sponsors or governing bodies don't want bad behavior associated with their respective brands, and will put pressure on the club or organization to quickly rectify the problem.

If it is an informal ride there will usually be a social media page (e.g., Facebook) used for communication (how else can you brag about the beating you laid down on everyone last ride).  You can use this to bring up your issue to "members".  If no action is taken, your next steps aren't as clear, but there are always option if you are creative (e.g., public shaming).  

How far you want to go really depends how big of an issue it is to you.  For a  bit of rowdiness I would personally not go as far as I have outlined (i.e., I would just contact organizers), but I would for more dangerous behavior (e.g., chasing Strava segments on shared bike/walking pathways).