I just sing/play songs in my head. When hypnogogia sets in, it actually turns into an audio hallucination (sometimes I have been tempted to get up and turn the radio off, until I remembered that it's only playing in my head)...when the dream starts...it goes away nicely. Though sometimes I have continued singing it in my head into the lucid dream, but could have stopped had I wanted to. I would not choose to listen to music during a WILD, and have heard too many horror stories about CDs skipping and weird songs coming on unexpectedly. I have entered a WILD listening to some nice holographic audio waves crashing though, but the sound of the waves didn't follow me into the dream world. White/pink noise is also tolerable.