I play a lot of poker and do a variation of this when I sit next to a particularly annoying player that just wants to talk constantly. With my headphones in I let them say whatever they are trying to say to me twice, then I look at them and take my headphones out of my ear and say, sorry, I couldn’t hear you, I have the noise cancellation on can you repeat. I let them repeat, I answer nicely, put the headphones back in and when they start talking to me again I repeat the process. Usually only takes once, sometimes twice. If that fails, I just ignore them because the noise cancellation on iPod pro 2’s is amazing. For the record, I only do this if someone won’t stop talking about nonsense for a long time, like 45 minutes or so. I am a very patient person. This just kind of demonstrates that their constant blabbing is requiring active work from me to hear, most people get the message.