Firstly, what can one say but sorry it has been so long. Becky was made redundant, and is now shuttling between Cheltenham and Derby, and I am ridiculously busy — something which should ease up about mid to late August. I will of course be trying to catch up on what has been happening in the world of spooks in the meantime, and hope to keep the blog interesting.
However, readers will recall that in my previous comments on this or my personal blog I referenced the fascinating work of Dr. Barrie Colvin. At that time the work was unpublished — and even in my Paranormal Review review of the SPR Study Day No.58 on Poltergeists: Then and Now I refused to reveal any details of the hypothesis until the journal article was out. Well now it is, in the April 2010 Journal of the Society for Psychical Research, and I want to briefly discuss it here.
I’m involved in an internet debate on a Dawkins successor forum, http://www.rationalskepticism.org (Richard Dawkins closed his own forum back in February, and this is one of the communities set up by emigres from there) where I had briefly mentioned Dr Colvin’s work in passing. Once the JSPR piece was published i wanted to discuss it more fully — and owing to tiredness and time pressures I may have made a hash of it, but I wrote a brief precis of key themes, which I thought may interest readers of this blog. However really you should read the original article, because it may be the single most important thing written on the poltergeist phenomena so far this century, in fact it probably is. It is ‘ The Acoustic Properties of Unexplained Rapping Sounds’ in the Journal of the Society for Psychical Research  Vol 73.2 Number 899 pp 65-93.”
At the time I last brought up Dr.Colvin’s research it was unpublished: now fortuitously it is in print, and we can discuss it in a little more depth.
Remember, this is not a lab experiment. Even if it was, we would want a plethora of different microphones to rule out the possibility that the equipment, not the sound itself, was causing the unusual acoustic characteristics. Instead we are looking at ten recordings from ‘the field’, from cases in which Dr Colvin was for the most part not involved – Andover (1981) being the exception. The other cases which provided recordings were
Sauchie, Scotland (1960) – from Broadcasting House, from the BBC recordings taken at the time.
has more on the case for those not familiar with it – Owen, A.R.G. Can We Explain the Poltergeist? New York: Helix Press / Garrett Publications, 1964 gives a full account by the principle investigator.
Thun, near Bern, Switzerland (1967) The recordings were taken from a CD.
Schleswig , Switzerland, (1967) taken from a CD.
Pursruck, Germany (1971) – from a recording by Prof. Hans Bender (16-bit stereo, 44100Hz)
Ipiranga, Brazil (1973) – recording by Guy Lyon Playfair taken during the IBPP investigation. More on the case can be found in Playfair’s 1975 book The Flying Cow.
La Machine, France (1973) – recording by Dr Alfred Krantz.
Enfield, England (1977) – from original reel to reel tapes, which was running “at the rather slow speed of 15/16 of inch per second” (Colvin 2010); recording taken by SPR investigator Maurice Grosse. A recent Channel 4 documentary on the case well worth watching can be seen here —
– you can see the equipment used and context.
Andover, England (1981) – investigated by Dr Colvin.
Santa Rosa, Brazil (1988) – taken from a recording made of a television broadcast (by TV Globo) on the case.
Euston Square, England (2000) This case has recordings by both Maurice Grosse and Mary Rose Barrington available.
Ten cases, none recent, because recordings of acoustic phenomena associated with poltergeists are by their nature difficult to collect: one need a poltergeist after all! The two Swiss cases are from a digital CD recording commercially available of recordings of parapsychological phenomena – it is impossible to say to what extent they have been edited and processed, so I would say they were VERY weak evidence. The Brazilian cases rely on recordings taken by Guy Lyon Playfair at the time, and by him off the TV, and he was present at Enfield – yet fraud seems unthinkable, given the dates, unless he somehow had access to very high end studio equipment and knowledge of acoustics in a pre-digital sound age. Therefore, I think that so long as we trust Dr Colvin’s acoustic analysis, the sound signatures he claims to detect in his varied collection of poltergeist sounds are authentic. Colvin’s claims are checkable — at least some of these recordings – the Enfield sounds and the two from the CD, and possibly if you are willing to approach the BBC Sauchie – are available in their original form to interested independent parties wishing to check the results. I suspect someone with appropriate acoustics knowledge could acquire copies of all the recordings by request to the SPR. (http://www.spr.ac.uk)
Adobe Audition http://www.adobe.com/products/audition/ was used for the analysis, in case anyone fancies trying a replication. I do favour a hands on approach as you all know by now!
So what does Colvin claim to have found? Well let’s start with a normal waveform. It follows a characteristic pattern – a wave form showing a sharp rise in amplitude or immediately to maximum amplitude, followed by a gradual decrease to zero. Adobe Audition has a free trial, but there is plenty of freeware on the web you can download which allows you to experiment with banging various substances yourself. I did so, analysing some sounds submitted by Wayne Morris from his paranormal investigation at Landguard Fort, Felixstowe last year, and found that the banging noises there followed the same type of acoustic signature I could get by kicking the wall or banging my desk – the above pattern, suggesting a normal explanation for those (non-poltergeist) sounds. Simple experimentation with a large number of substances demonstrated that the pattern is consistent, and that Colvin’s comment on this is completely correct. I encourage everyone reading to try this for themselves, to familiarise themselves with the standard way the amplitude and frequency can be analysed and the common pattern one sees.
Colvin gives a couple examples of frequency ranges in mundane sounds – a hammer hitting an oak desk gives a frequency band of mainly 50Hz to 300Hz – a teaspoon on a crystal glass 300Hz to 3000Hz, with a decay of amplitude lasting three seconds. What one might expect in short. However, once again I strongly suggest a few minutes experimentation at home, and posting the results??? Really, do try!
So how do the acoustic properties of the raps in the ten cases in question vary? They show a consistently odd rise in amplitude, a waveform that slowly rises rather building to a sudden peak and then falling away. One can test this on the knocks from the Channel 4 shows recordings from Enfield I guess, or armed with some money, order the CD Colvin took the Swiss cases from: I have too date done neither. Given the fact the JSPR article is clearly copyright, I shall simply reproduce just two of the figures here, showing a knock deliberately made by Grosse at Enfield as he tried to replicate the noises,and one of the anomalous raps…
So why do the waveforms show these unusual characteristics? Colvin thought of a possibility, which shows his critical thinking and thoroughness —
Dr. Barrie Colvin, [i]JSPR[/i] 73.2, Number 899, April 2010 wrote:
One of the possible normal explanations put forward to explain the results is that certain types of microphones may give rise to the anomalous results because of their inherent qualities and mode of operation. A microphone is simply a sensor that converts sound in to an electrical signal. The most common types consist of a thin membrane that vibrates in response to sound pressure.
I actually did not know much about how microphones work. This was helpful!
Dr. Barrie Colvin, [i]JSPR [/i]73.2, Number 899, April 2010 wrote:
This movement is subsequently translated in to an electrical signal using one of several techniques. Most examples use electromagnetic induction, capacitance change, piezoelectric generation or light modulation to convert the mechanical vibration of the signal to an electrical signal. The question that arises is relation to a short impulse such as a rap is whether or not there could a be a delay between production of the sound and vibration of the membrane. Could the inertia of the membrane, particularly with microphones dating back to the 1970’s, lead to a relatively slow increase to maximum amplitude when subjected to a short burst of acoustic energy?
This is why I suggested in a lab set up we would require several microphones, of different makes, models and manufacture. Colvin experimented making raps with a number of microphones dating from 1959 (including the Phillips EL3549A & the EL3782 with impedance 583 ohms) to present day microphones, looking at the waveforms, to falsify this hypothesis. Again, with old microphones common in attics if my house is anything to go by, I suggest interested parties can do at home…
However there is another reason to believe the results are not an artefact of the microphones. Three of the recordings include the investigators making their own raps. These investigator produced raps possess the normal waveform, not the slow rise in amplitude associated with the “poltergeist knockings”. As such, we have an inadvertent control, which demonstrates the microphone was NOT the source of the unusual waveforms.
Colvin has managed to find similar acoustic waveforms to those recorded in these ten cases – in recordings of seismic activity. His paper gives two examples – a recording of an earthquake at Ascension Island in 2007, and a British Geological Survey recording of a seismic event at Folkestone in 2009, described as being “like an explosion”. Colvin theorises that the sound signatures associated with the poltergeist events imply they are caused by a sudden release of tension or alteration in the substance of an object, not with as one would assume a rapping of one thing on another. An intriguing suggestion, but clearly one that requires further high quality recordings to test adequately.
It’s a fascinating article, one of the best I have read in a long while. I want to experiment now, and above all to try and collect more recordings from cases to give to Dr Colvin. I strongly suggest all reader of this blog try to lay their hands upon the latest JSPR to read the article as soon as possible…