Scientific evidence of poltergeist knocking?

[PPI Brian]

An analysis by Dr. Barrie Colvin of recordings of alleged poltergeist knocking obtained from around the world over a 40-year period indicates that raps and knocking sounds recorded in alleged poltergeist cases show quite a different acoustic pattern, or sound signature, than those produced by ordinary means. So how is the anomalous sound generated? "There is evidence which points to the sound arising from within the structure of a material rather than from the surface of it, as would be the case with a normally-produced rapping sound."

http://www.spr.ac.uk/main/news/colvin-acoustic-properties-poltergeist-rapping

[PPI Tracy]

Several questions running around in my head.  (among other critters)

The article stated that : "The sample involved 10 separate recordings recorded on different recording apparatus"   

How can you compare them when the sound recorded isn't #1: coming from the same source and #2: recorded by the same device.  Can you really compare them sound for sound in that manner?  Also, you cannot predict a poltergeist occurrence so how did they "know" it was of even of that origin?

I guess what I am saying is how can you compare apples to apples if you have apples to rutabagas

[Damian]

I see what you're saying Tracy.  I think what the article is driving at, and why they talk about various recordings from various events, is to illustrate that regardless of the type of recorder, the audio quality, the location, and the event, the claimed poltergeist rappings have a noticeably different and unexplained audio structure.  It seems that the key theory the author(s) is communicating is that poltergeist knocking appears to originate from within a structure rather than it's surface.

That's my interpretation of it anyway.

Cool article and a very interesting theory!  This might be another great experiment for us to create, execute, and interpret.  What do you guys think...any merit to this?  I wonder if Audacity would allow us to visually interpret recorded audio sufficiently...

[PPI Tracy]

Well color me stupid.   

Naw...I hear what you're saying.  Makes sense.

[PPI Brian]

Apparently Dr. Colvin performed a spectrographic analysis of alleged poltergeist rappings over a considerable period of time. SPR has been around for over one hundred years, and if this claim were made by any other paranormal group, I would seriously doubt their findings. I have been wanting to do a spectrographic analysis of a sample of EVPs our group collectively believes to be paranormal and try to determine a spectrum that sets it apart from normally occurring speech -- or firmly places it within the normal range of human speech. Either finding would be very intriguing. 

I would really like to read the entire article, but you have to join their group in order to receive their newsletter. Their subscription is 60 Brittish pounds sterling per year (a little over $90.00 U.S. Dollars). Bummer! 

Perhaps Tim would be so kind as to check the Public Library database to see if we could borrow a copy from somewhere?