A pair of Bose QC25's has been my most objectively productive purchase this last year. I highly recommend anyone in an open plan office to buy some, or something like them - they're expensive but worth every cent.
My point was that as long as you're buying headphones anyway, buy some good noise-cancelling ones, and you'll mitigate a lot of the risks in the article. It does suck that it's on employees to do this, but here we are.