Sometimes they will all talk at the same time. For instance, I'll be explaining an assignment using Teach! OK! but at times I will just want the class to remind themselves of something such as an MLA format detail. So I might just give a directive like, "Turn to your neighbor, wagging your finger, and say "Don't forget, 12 point Times New Roman ONLY for this paper!" " For this, they will all just say it at each other simultaneously, and the finger wagging gets a laugh out of them. However, most of the Teach! OK! moments are one at a time, so when I walk around I can correct/encourage/assess each student.
As for the noise, I happen to be next door to a very traditional "all students must be silent at all times" sort of teacher and I am sure he hates all the noise from my room, but my concerns are for my students' learning and not for other teachers.
Having said that, I did have a group who were very high level, affluent students who seemed to mock the WBT. Once when I said, "Teach!" They purposefully were so animated and enthusiastic they completely drowned me out so even when I said, "Class!" I could NOT be heard. But it's all ok, because it just got points for ME on the scoreboard, they ended up with extra h/w and they never did it again.