Last night, I sat in my null space and meditated. I focused on a mental image of Osiris. This was a very good meditation. I was very focused. I didn't not feel that uplifting astral feeling. Suddenly, I heard a sound like the wall behind me was cracking apart. This caught my attention for only but a moment.
Suddenly there was loud buzz like the hum of an electric transformer. Something touched me and passed very quickly. The sounds stopped. This broke my meditation.
Edit: The sound of the wall breaking up was not one big break. It was more like a crumbling by force. It is hard to judge time in a meditative state. My guess is the sound lasted two minutes or so.