Studies like these don't look at the holistic picture. Productivity isn't just a function of minimal distractions, but a combination of a bunch of items.

In particular to this study, it doesn't account for employee happiness. Personally, I and all of my employees, are far happier with an open space. Happy employees, make for productive and loyal employees.

I would gladly take an open space knowing the trade off that it might be a little more distracting, but a much more pleasant environment to work in.