I've used earplugs but haven't so much since I got a pair of Bose QC 15 noise-cancelling headphones. They work wonders for blocking out background conversation.
For moderate levels and when I am in a relaxed state to begin with, I can leave the destructive interference feature off. The insulation all by itself is very effective. If the noise is really annoying (or if I'm anxious or tired or something) I can turn on the noise-cancellation. It can feel a little awkward at first and I have a vague sense that it might not be good for my ears, but essentially all external distractions just fade into the background. To interrupt me you basically have to walk up and tap on my desk.
For moderate levels and when I am in a relaxed state to begin with, I can leave the destructive interference feature off. The insulation all by itself is very effective. If the noise is really annoying (or if I'm anxious or tired or something) I can turn on the noise-cancellation. It can feel a little awkward at first and I have a vague sense that it might not be good for my ears, but essentially all external distractions just fade into the background. To interrupt me you basically have to walk up and tap on my desk.