Although there are those who may disagree with me, in my reading and studies SP accompanied by loud noises is the beginning of an astral projection experience. In my opinion you were about to leave your body.

You can test SP, and break it, simply by thinking about moving your pinky. You can return to your body, if you leave, the same way. In the in-between state try mentally thinking out loud, "Now I leave my body!" or "Now I Lucid Dream!" - whichever you wish to do. Use your own words, state your intention as loudly as you can in your mind as if it were a command you expect to be obeyed.
- DreamBliss