I tune things out when I crochet, and I also do this when I blog about crochet. Actually, I do this with pretty much any mildly repetitive task that involves the smallest bit of focus. Tuning things out is great for my projects, because it means that I mess up less often and get things done a lot faster. It does, however drive my boyfriend bonkers. I literally do not hear when he is talking to me. If he needs to tell me something, he will have to actually nudge me on the shoulder. Sometimes more than once. Okay, usually more than once.
This is why I tend to crochet mostly when I'm home alone. I do have a group that I meet with every two weeks or so, which I love. They are a great bunch, and that's why I try really hard to not get super focused. I don't want to tune out any of them. This usually means that I work a tiny bit on multiple projects, spending more time hanging out than doing any serious work. Crocheting at home alone isn't really a bad thing though. I enjoy my time alone, I get bunches done, and nobody is bothered when I ignore the world.