"21) The biggest problem at many parties is an endless escalation of volume. If you know how to fix this, let me know."

Only way I know is to have a porch, garage, or other connected-but-not-the-same-space open for people to spill into.

If it's the kind of party where there's music, stop the music. Everyone will hush, expecting for something to happen. After a minute or two, turn the music back on at a lower volume and the crowd will adjust.

Spaces, as in have multiple locations for smaller groups to enjoy the scene. There is a real reason that some of the better night clubs are not a single spralling space, but a multi-floor building with each floor sub sectioned into dozens of little back to back living room like couch setups. Intimacy works.

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.

Sound deadening and insulation, whether purpose-made or simply walls/trees/incidental stuff. Fifty people in a 200sq/ft space will almost always louder than twenty-five people in two 100sq/ft spaces connected by a doorway.

Unless the space has amazing purpose-built acoustic qualities, put physics obstructions between groups of people (walls, doors, bushes, trees, fences, whatever).

If a house-party is unbearably loud, there's just too many people for the space, or there's some anomaly that is concentrating too many people in one area.

On the flip side, is there such a thing as a good, quiet party? Only if it's very small.

db meters are available for purchase, which helps with the problem of not being sure how loud is loud while in an altered state of consciousness and need something to compare the volume to.

That one struck me oddly; escalation of volume is a problem you want to have. If the party is quiet, it feels dead, and people leave early. I always used to deliberately leave music playing at a level which would require people to speak up a bit, so it would feel like something was happening right from the start; the glorious roaring chaos would then build of its own accord.

Ideally this is something we could solve with data, with letting people see the trend over time, with some call to action moments to quiet the fuck down for a minute, reset the otherwise only up-moving gauge.

Every now and then I'll resort to just turning the volume up so that people give up. No, sorry, conversation is already basically impossible except via shouting, so I'm going to up the volume to prevent conversations for a little bit, interrupt the flow, then go back down.

I'd love some volume meters that have very visible displays. It's in the red! Everyone chill out! Or ideally presenting some view over time. Little tablet screens placed about or above that show some logarithmic time scale of volume, so people can calibrate, see the bad trend line. There need to be enough different volume-over-time systems about so people know where the problem really is coming from too. Most people at the party are just trying to talk, so the real art of debugging this nonsense is finding who is being extra loud, and introducing some observability to let the specific worst offenders fix their specific loudness issues, then the rest of the party can de-escalate too.