[iafan]

Active noise cancellation headphones (without playing music). Bought ones recently and can't be happier. Works both in office and when working from home, and are great in cancelling the background noise (like HVAC) and lowering the overall volume of speech to the extent it doesn't bother.

I do, however, usually combine noise cancellation with a — now pretty quiet — background electronic music with no voice, which I've found helps me concentrate.