I found interrupt rate increased for open plan by, oh, probably a factor of ten. Look, VLM isn't talking, therefore he must not be doing anything, lets ask him about last nights TV episode. If the cube wall is high enough that you can't see if the worker drone is in there much less on the phone (aka working) or actually working as in thinking, then you don't just yell at the guy across the room.
I notice a massive impedance bump between the "knowledge workers" and the "talkers". Engineering and Finance and operations got along nearly perfectly because both know that not talking does not mean not working aka ready for interrupt please bug me. On the other hand management / customer service / sales, if they're not talking they're not working, so interrupt rate was horrible from those types, hmm I have a problem and those three are talking about football so they're busy, and that guy's talking to his wife on the phone so he's busy, I know I'll bug that guy looking at a component datasheet, obviously he's the only one here not doing anything. Marketing types were kind of in between, some understand that thinking is work, some don't.