Whilst on a case in an old house in Scotland near a ruined abbey, I experienced a memorable accustic event. It occured in a long stone barrel vaulted room at the bottom of the house, probably just below ground level. Whilst we we were covering this area my fellow investiagtors and I heard the unmistakable chanting and singing of monks. No mistake, no error, monks chanting and singing.
We hung around far longer than any sane person would have. Long enough to hear the ghostly voices stop. Then we heard "And that's all from BBC Scotland etc etc" followed by the national anthem.
Somehow the radio waves had travelled to the room, maybe through the stone, I'm not sure, but and when they hit the barrel room we got to hear the show.
If we had fled when we heard the monks there would be a story now of singing monks haunting a house. If there is a moral to this story it's always try to see the experience through to the end if you are lucky enough to have one and remember there may be a natural explanation even though it looks very unlikey.