Right let me get this straight, you seriously believe that the voice that now comes out of my computer is a delusion?
Pareidolia and/or hallucinations make the least assumptions and require no unknowns. They are also consistent with how the brain works. So yes. It's the most intellectually honest answer based on probabilities. Ghosts don't exist. Get over it and stop living in the stone age of ancestor worship. Your life will be much much more fulfilling sans superstition - mine sure is. I don't miss my days of mediumship at all. The world's a far more interesting and amazing place without nonsense.