Becoming Lucid

While you're in a non lucid dream, can you hear whats happening in real life around you? Because I can remember dreams where it all of a sudden starts to thunder, and I wake up to a thunderstorm IRL. Also, I sometimes hear my alarm clock in my dreams and I look around trying to figure out where the noise is coming from, then I wake up.

If this is true, would it be possible to trigger lucidity by wearing headphones to bed, and during a period of REM sleep, have the headphones play a recording that would say "this is a dream" a few times over and over. I would hear this in my dream, right? and then I would realize that it is a dream and become lucid? This would be awesome!

Sometimes sounds and bright lights in waking life can appear in your dream, but usually audio sounds distorted and the lights are changed into something the dream finds more plausible - eg. a car's headlights or something.

It's possible to use sounds to trigger lucidity, but you have to be aware enough to recognize that the sound's actually trying to say that you're dreaming. This pretty much makes them unnecessary to gain lucidity. After all, a DC could be saying over and over that you're dreaming, but if you're not aware enough, it'll pass right over you.