Would digital recorders work? A couple times I went to my local graveyard and set my digital recorder on a random grave stone to record all night (yeah I biked in at night :O ) Then I would retrieve it in the mornings (tip: remember whose stone you put put your recorder on!) I never got anything in those 3 nights, but one of the nights the recorder was mysteriously shut off when i retrieved it. Strange -- because I even had manual 'lock' button switched on! Upon retrieval It had about an hour and a half of relative graveyard silence, then the file abruptly ended without error. Battery full, plenty of memory available...
Digital recorders should work quite well, Maphoo. It's what I've used in the past and I think many investigators use them as well. Strange, tho, how you had that on manual lock and poof. Hmmmmmm. Makes ya wonder.....
One way you can do it is make a mic silencer. Basically you take a headphone jack, take off the headphones, and complete a circuit so the wires bring the power directly back to the listening device. A long cord is great too. I think you can do this without extra wires, depending on how much interference your recorder gets naturally. If youre talking and looking for answers, write your questions on a clipboard, and write down the minutes and seconds that are on the recorder when you ask, kind of like a polygraph.
This way is great, that way wind and someone whispering when you dont recall someone whispering, wont interfere with readings.