That is often coincident w cannibis consumption and if they aren't super drunk people can be prompted politely to bring their voices down. With the music itself volume is best moved gradually enough to not be noticed. Main thing as a host is to guard the volume. It is always a balance to make people want to dance, to provide shelter for intimate conversations which don't travel against too loud where shouting and law enforcement may arise. Rock musicians and their engineers eventually figured out an audience can match nearly any decible level below 110 and can move above it.