I don't actually need anything playing on the headphones to effectively block out voices, even nearby ones. I compared my HD280s agains active noise-cancelling

I don't actually need anything playing on the headphones to effectively block out voices, even nearby ones. I compared my HD280s agains active noise-cancelling headphones and the Sennheisers blocked talking much more effectively, because there's that much more material between your ears and the outside world.