HOW DOES ANYONE GET ANY WORK DONE IN AN OPEN PLAN OFFICE??? Sorry, that just burst out

Now, thinking back to a LONG time ago when I was working in development teams of maybe 2-3-4-5 engineers it did actually seem to work well for us, we could share and bounce around ideas, however when I started managing the same team in a large office space it was clear that those discussions were also extremely disruptive to anyone else in the same office area **. The best arrangement I've worked in for team engineering was probably when we had 5 of us in a single (fairly soundproof) office.
Equally, having been involved in business management, I am very well aware that large open plan offices are cheap and flexible, but personally I'm suspicious of the impact on overall productivity, at least for engineering functions.
I haven't even started discussing getting the air conditioning set right for everybody...
Does anyone here have any views? It's a serious point.
Right, I will stick my headphones on, play some brown noise, and try again.
Cheers,
Andy
* Our company Mentoring scheme is being audited by the IET today, hence the fact I've been asked to work at HQ and prepare to be quizzed by the IET!
** I led a raiding party and commandeered a soundproof space away from anyone else where that team could work, before any actual murders occurred. I ignored the suggestions from the rest of the engineers that it should also be made airtight...