[lolinder]

I did, but that was never enough: even 37dB ear muffs aren't enough to completely suppress the noise of a conversation happening nearby, but the ear muffs plus the walls and the door are.

And, of course, as others point out, the auditory distractions are only part of the problem with an open floor plan.

[qumpis]

I've got good results with white noise, not sure if that's something that would work for you. And of course I didn't suggest that this eliminates other distractions.