I don't know the technical details, but: I've been on world hops with groups where occasionally I'd hear an annoying noise playing at full volume, not spatialized or anything, even when I was totally alone in a portion of the map; and after hearing the same noise again in a later world, I realised it must be coming from someone's avatar.

If it's currently allowed for people to put non-spatialized sounds on their avatar: it shouldn't be. If it already ISN'T allowed: then this is a bug report, because people are doing it anyway. I'm sorry I don't have more details but I thought I'd at least get the ball rolling.