Thursday, 21 February 2013

On the Origin of Ghostly Sounds

Ghostly soundsStanding in a familiar room, I heard a faint mechanical squeaking sound occurring every few seconds or so. It sounded strongly like it was in the room, which was highly surprising to me. Despite the fact that I knew there was nothing that could cause such a noise in the room, I searched it anyway. Finding nothing, I listened in the part of the room furthest from the window and then next to it. The sound was loudest near the window but not by much. So it COULD be a sound source outside the building OR inside near the window. I could not decide what direction the sound was coming from. Later, when I went outside, I heard the same sound but much louder. I was then able to pick up its direction. It appeared to be coming from a gate which was being pulled around by the stiff breeze.

So what did I take from this less than riveting experience? Firstly, the fact that I couldn't tell which direction the noise was coming from when inside should have given me a clue that it was coming from outside. The sound will have been partly transmitted and partly diffracted (see diagram: routes T and D) making its origin difficult to tell inside the room. Secondly (WDTHDWP), it reminded me that people who record EVP on ghost vigils will often say the voice cannot have come from outside the building. They say this on the basis that the windows and doors were all closed and curtains drawn. However, if you stand in an empty building with all the doors, windows and curtains closed (and no appliances on) you will find that, in most cases, you CAN hear sounds quite plainly from outside! Unless the building has double glazing and sound proof doors, some noise will almost certainly get in from outside, including voices. And at night (when most ghost vigils are held) voices from outside are easier to hear because there is less background noise, both inside and outside.

So, if you get a really convincing-sounding unexplained voice recorded on a ghost vigil, bear in mind that it COULD be a real voice coming from outside the room (and maybe outside the building). Sound recorders are often highly sensitive and able to pick up faint (but real) voices that nearby witnesses can't hear, or don't notice. And being a totally real voice, it's going to sound pretty convincing evidence that something paranormal is going on.

When making sound recordings during paranormal investigation, it is better to use multiple recorders (all of the same model and with the same settings) simultaneously, rather than just one. For instance, suppose you placed your 'main' recorder in the centre of a room, you could put others by every window and door to the room. If an interesting sound appears on several recorders you can then compare them. When analyzing sounds, a second recording of the same sound is very useful indeed.

Suppose you get an apparent human voice on the 'main' recorder in the centre of the room and a sound also appears at precisely the same time on one of the other recordings. That other recording may be recognizable as something other than a voice, like a creaking chair or paper being shuffled. This would tend to indicate that the 'voice' has mundane origins ('formant noise'). You could, thus, eliminate that recording from consideration as possibly paranormal.

But what if the same voice is heard on a second recorder, only clearer and more distinct? If that recording was made by a window, it makes it likely that the voice originated outside the building. This means that you cannot then rule out the possibility that it was an entirely normal human voice. So, again, you could eliminate that recording because it would be impossible to show it did NOT have natural origins.

Thus multiple recorders can help to eliminate some recordings where natural causes cannot be ruled out in a way a single recorder cannot. For more on analyzing EVP recordings, see here. For more on recording weird sounds see here.

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