Dreams and Catalysts.

[zenmaster]

I get the crown-chakra energy thing quite often - I see the white light. It could very well be due to imbalance of lower chakras.
There are also associated electromagnetic energies (in Ra's terms) that will subtly influence the inner ear to create 'tones'.

Another thing I've experienced in meditation is that alien contact with the actual impression of the entity's form - rather amazing and seemingly random - not the familiar bipedal entity.