Don’t ask people to please keep it down because there's a baby present
Most people will be cool, like the dude to the left, and voluntarily modify their behavior, thereby earning the ultimate gift: "napkin". If they're not cool, remember: you have the exact same rights you had before fatherhood, no more, no less. If someone’s being so loud it’s bothering even people with fully developed ear canals, definitely ask them to lower the volume, and threaten to fight them if they don’t. Just don’t make it about your baby, who you brought here, and definitely did not have to bring here.