How did you conclude your speaker was hacked? There could be a technical fault. Take a look here: 

You're right I am jumping to conclusions. I just don't have another explanation. It was sudden, it was at higher than maximum volume, it was a terrible pre-recorded sound, not the sound of a glitching speaker. It was some kind of screaming.  I suppose it could have been some awful track that somehow got into my playlist... How can I see track history? 

My security camera may have caught the sound, not video. I'll check that out. 

I was alone at 1am, family sleeping. The only other thing is it could have been an actual track that got on in rotation. I can't believe that though. 

I don’t think you can. You could make a diagnose if it happens again (within ten minutes of it happening) and call Sonos to see if there’s something wrong. 
 

Just a thought: did you let anyone play on your system via Spotify Connect?

@BBooch,
Yep, it sounds like a Spotify ‘connect’ issue, but maybe, just as a precaution, it would be worthwhile reviewing the local network security and maybe change the router Admin/WiFi passwords and update the network/sonos devices to reflect those changes aswell.

Like a valuable item inside your Home is being protected by your Home security (locks on doors etc), Sonos is fully protected by your local network and if that’s been breached, then you need to put ‘new locks’ on the door by changing the passwords mentioned. I would start there until you can perhaps discover more info.

There was a successful triple hack of Sonos One this summer where the hack netted those over $105,000.00 …

https://thehackernews.com/2023/05/hackers-win-105000-for-reporting.html?m=1

Make sure you patch your system…

I guess it’s always good to keep any manufacturer-supported ‘internet connected’ devices up-to-date with the latest firmware/software. Those devices where the manufacturer no longer provides security updates should be replaced. Fortunately, Sonos continue to support ALL their network players, even those manufactured/released way back in 2005. Not many hardware providers tend to give that type of service. It’s something perhaps many may take for granted, but I’m extremely grateful for that long term support and appreciate the security updates.