Apparently synchronized speakers grouped to zones, with the possibility for the zones to overlap so that one speaker could be in multiple zones rather than just one. To quote the judge:

> Then, in 2019, Sonos filed continuation applications for the patents in suit. To get around the prior art, Sonos sought to patent zone scenes with a new twist: overlap. With overlap, a zone player could be a member of more than one zone scene at the same time

It turns out that what Sonos did was even more scummy than implied by lights0123. In addition to this being something Sonos didn't implement until much later, it was actually Google who first suggested this idea to Sonos.

> This was thirteen years after Sonos filed the provisional application, but also five years after Google had itself disclosed overlapping zone scenes to Sonos, and four years after Google had released products that implemented the feature.

It's interesting to read the comments from half a year ago with this knowledge: https://news.ycombinator.com/item?id=36093764