Category Archives: Poltergeist Research

Polter-Censored???


I have been horrendously busy recently, and amusing myself with stuff like the 1st Cheltenham Paranormal Festival, so the blog has fallen rather quiet. There was one odd little incident, exactly the kind of thing one forgets. After my talk, during the ghost hunt, I walked in to the auditorium gents, and was struck on the shoulder by a button. My leather jacket has a strap on each shoulder with a button – since before Christmas the one on the left had been missing. As I walked in, it suddenly returned – and struck me lightly, before clattering to the floor. I was the only person in the gents, and there was no button I could find before in the jacket to replace it, as it annoyed me as the strap flapped free. Perhaps it had been caught up in my jacket for months – I guess it must have, or I had a very inconsequential and trivial poltergeist experience!

Anyway, today I’m moved to post by something a little odd — it seems some sceptics may be actually getting as loony as some believers can be, or maybe it is just — I don’t know, I just don’t get censorship on scientific issues. I guess the people who do these things would deny it was science –call it pseudo science. So what am I on about?

Martyn McLaughlin in The Scotsman on Sunday published a piece on Dr Barrie Colvin’s research. I’ll quote a bit of it here, for ease of  reference –

Ghostly rapping can’t be faked, research shows

Published Date: 30 January 2011
By Martyn McLaughlin
THEY are unexplained phenomena that have baffled scientists and sent chills down the spines of unwitting bystanders.

But the eerie knocking sounds allegedly made by poltergeists could not be made any other way, according to new research.
A lecture taking place this week at the University of Glasgow will present evidence for a strange audio pattern common to paranormal incidents.

(Read more)

Now as it happens I disagree. I was a strong advocate of the research, but in experiments conducted last year with friends from Rational Skepticism forum I found no difference between the waveforms of poltergeist sound files provided by Dr Colvin, and those I made by banging on furniture, under certain conditions. There has been a long and technical discussion on this blog – I have been fascinated since the first, and still think the JSPR paper was very important, but I am frustrated I could not replicate the findings. I am now waiting for others to try, and see what they find.  If you have not been following the discussion, my original article on the JSPR paper is here, followed by our experiments and critique  here, and a further piece on the polt raps here.

As one would expect, there has been a fair exchange of views, lots of speculation and refinement of hypotheses, and ultimately I think we all agree that more experimentation and as Dr Colvin said in his original article more good recordings from cases are needed. I think we also need to agree on what constitutes a slow attack, that is a sustained rise to maximum amplitude.  Still, so far I seem to be one of the few “critics” of the research – ironically given my admiration for Dr Colvin et al, and my firm commitment to poltergeist research.

Anyway today I saw the Scotsman on Sunday piece, and tried to link it to my Facebook. I received a message from Facebook saying that link had been reported as spam, and was therefore blocked. I was incredulous. I have written to Facebook using the report, asking the article be un-flagged – but was puzzles me is why it was flagged as spam in the first place. I may disagree with the article, but that is just ridiculous – censorship.

I am going to be paranoid here, and say that I think it was reported as spam by a sceptic, probably someone who sees themselves as a scientist, and who has never even read Dr Colvin’s paper.  Why do I believe this, rather than blaming some dour Scottish religious type? Well firstly religious types tend to welcome evidence for “supernatural” manifestations, especially polts which are often demonic in their attributes and behaviour and the fear they instil, even if not demonic in essence – whatever demonic may mean, exactly. Secondly, bitter experience of people refusing to listen when I discuss rationally evidence for “paranormal” claims. However for me the clincher was when I was trying to edit the Society for Psychical Research‘s and other parapsychological organisations wikipedia articles, often vandalised in the past, and edit after edit was rejected. Many times that was fair – I had messed up the edit – but eventually I realised that even though my edits were on historical matters and referenced, they seemed to arouse considerable hostility and raw emotion in some people.

The worst example I ever saw of this was after a well known parapsychologist and biologist was physically attacked and wounded, when on a sceptic’s  forum (the JREF) I saw someone post a horrific  comment praising the action, and hoping – well you get the drift. When people get so angry they say things like that, something is wrong.  Now let’s be fair – the comments were edited away, the JREF mods quickly acted as I would expect of them (I have come to know many of them through the forum as good people, and it is VERY well run usually) – but honestly, the couple of nutjobs who displayed real hatred scared me a bit.

Now every forum has nutjobs, and as recent experiments in social psychology has shown, attitudes harden rather than being softened in a group forum which faces outsiders posting contrary opinions.  In fact in the case of the JREF, the people who posted the material I found offensive were NOT regular forum types; my experience of sceptic forums is that people become far mellower and nicer over the years, ditto pretty much any forum, as they get used to the forum environment, and communicating on the interweb.

So I suspect that this latest piece of vandalism was just an aggrieved nutcase with a lot of faith, who KNEW this was pseudo-science, who therefore hit a spam button to stop this pernicious threat to their cosy FAITH go unseen by the eyes of poor gullible dupes like all of us. Such people just annoy the hell out of me — because they are not sceptics, they are simply bigots. Still I could be wrong – maybe there was some other reason for The Scotsman on Sunday being blocked – but somehow I doubt it.

It’s a sad,  sad world when people on either side of the great paranormal debate can’t even listen to one anothers opinions and try to formulate a rational critique :(

cj x

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Poltergeist Raps: JG experiments


I only know JG as a commentator on this blog, but I asked their permission to publish some comment they made on Dr Barrie Colvin’s paper from the JSPR which was the subject of my last piece. They cheerfully granted me permission, so here is JG’s research. Please note I am not the author; JG is – so questions should be directed to he or she, by commenting here on the blog!

JG writes –

“I decided to test the theory that the delay in reaching peak sound intensity (the ‘attack’), seen in the poltergeist acoustics paper, might be primarily caused by sound reflections from room walls.

First I tried making successive recordings of a knocking sound at increasing distances from the recorder. As the distance increased, the proportion of the sound arriving from reflections off walls should increase relative to that arriving directly from the source. This showed a significant increased attack but not enough.

Then I tried having the sound source around a corner, so there was a wall blocking the most direct path of the sound. This consistently produced an attack around an order of magnitude longer compared to a direct line of sight recording. The actual attack length was highly sensitive to the precise position of the sound source. Trying a large piece of furniture between the sound source and the recorder also produced a significant lengthening of the attack, though not as big.

The most likely explanation for the large lengthening of the attack time, when the source and recorder are separated around a corner, or some other large object, is the difference in different path lengths taken by the sound. With a heavy object or wall absorbing most of the sound taking the direct path, the remaining sound must either be diffracted or reflected to reach the recorder. The diffracted path closely follows the outside of the obstructing objects and always arrives quite quickly at the recorder. However, a significant proportion of the reflected sound must go via multiple wall surfaces in order to circumvent the obstruction. It is this big difference between the relatively direct diffracted path and the much longer reflected route that causes the longer attack.

So, unless the sound source and recorder are in direct line of sight of each other, there is likely to be a significant lengthening of the attack, of the type seen in the paper. The magnitude of that lengthening will depend on the precise layout of the room and be highly sensitive to relatively small changes in the relative position of sound source and recorder.  This is because of the many different  reflection paths that are possible.

Typical attack times when there is line of sight between source and recorder is in milliseconds. When there is a bulky obstruction between them it goes up to hundredths of a second. This makes sense since sound travels at about 340 m/s in air and the extra path length due to reflection (often multiple) will be in the order of metres up to low tens of metres. This is due to the diagonal paths taken by reflections to cross rooms that have wall lengths typically of a few metres.

Thus, if sound reflection is the cause of the slow attack in the poltergeist cases in the paper, you would expect the delay to all be in the region of hundredths of a second. Much longer or shorter would suggest that there must be some alternative explanation.

I decided to see if the figures from the paper itself agreed with this prediction. It is just possible to make out the time scales in the figures in the paper. Thus, it was possible to quantify, approximately, the attack times in the cases in the paper.

So here are the results. The figures are the approximate attack time in seconds, followed by a length in metres. By multiplying the time by 340 m/s you can see how much longer the bulk to the reflected waves travelled compared to diffracted ones (assuming the hypothesis is valid).

  • Andover peak intensity after 0.03s (extra path length implied 10.2m)
  • Euston square (1) 0.025s (8.5m)
  • Euston Square (2) 0.007s (2.4m)
  • Sauchie 0.04s (13.6m)
  • Thun 0.02s (6.8m)
  • Schleswig 0.015s (5.1m)
  • Pursruck 0.02s (6.8m)
  • Ipiranga 0.05s (17m)
  • La machine 0.04s (13.6m)
  • Enfield 0.01s (3.4m)

The figures are reasonably consistent with each other and all fall within the expected range, so supporting the hypothesis that sound reflections round an obstruction are likely to be the primary reason for the slow attack.

The delay in the arrival of sound from reflection would also tend to extend the overall length of a rap compared to one seen in line of sight from the recorder. Also, if the sound source is relatively remote from the recorder, as the figures above suggest, the higher frequencies will be missing as these are preferentially absorbed by the intervening air.”

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Knocking away the poltergeist evidence? A follow up on Dr. Colvin’s JSPR paper


It’s been a long time since JG posted comments on the piece I wrote on Dr Colvin’s JSPR paper that started me thinking about running some tests to attempt to falsify the hypothesis offered in that interesting article. I emailed Dr Colvin who very kindly sent me a selection of .wav files so I could look at them. My earlier piece examines Dr Colvin’s paper in detail; however essentially he postulates based on recordings from a number of purported poltergeist cases that the waveform characteristics of sounds made by poltergeists are unusual, with a slow attack and slow decline. Have a look at my earlier post if you don’t follow, and all should become clear. In this post I describe a simple test we did on this idea, and the results…

I had become intensely interested in the issue while debating Campermon over at Rational Skepticism forum. He raised an interesting possibility – if the sound were in fact anomalous, the sustained attack/delayed decline might be due to them not being raps at all, but two surfaces rubbing together – abrasion. As he pointed out, that would produce a waveform similar to that we were looking for, similar to recordings of seismic activity which are after all abrasion on a vast scale.  So I downloaded a 30 day trial of Adobe Audition (I don’t have the money to purchase a full copy, so don’t expect much more from me on this!) and started experimenting…

As you can see, this looks a lot like the waveform we are looking for – Campermon’s scratching hypothesis was vindicated. However there was a problem — it sounded wrong, nothing like a “rap”, and nothing like the recordings I had been sent.

So then we started experimenting in earnest. I made a number of control files, simply by banging furniture in my basement: one was Lisa jumping on the floor above, and one was the abrasion of a coffee mug along the desk. Then with 12 wav files total, including the anomalous ones, I submitted them to Campermon, GrahamH and Twistor59. I wish I could use their real rather than forum names but I would have to ask their permission  (and what they actually are)  so they can reveal themselves if they want).

The Test Files

All of the waveforms for these twelve files can be viewed here on Campermon’s site. I may as well reproduce them here!

waveform from experiment

CJ1

waveform

CJ2

waveform

CJ3

waveform

CJ4

waveform

CJ5

waveform

CJ6

waveform

CJ7

waveform

CJ8

waveform

CJ9

waveform

CJ10

waveform

CJ11

waveform

CJ12

Can you spot the four “genuine poltergeist raps” from the files???  We couldn’t. Well I could, because I created the other eight and prepared the blind test, but the others were not so sure.

Interpreting the Results

The problem was that several of the waveforms created by banging furniture by me look like the supposedly anomalous waveforms. Number 6 is just me scraping a coffee mug on the desk – we removed that from most of our analysis, as it sounded so different.   Just for the record the “genuine poltergeist”  files (in that they were recorded at poltergeist cases) are 1,4, 9 and 12. We decided the only way forward was a less subjective numerical analysis of the data.

A problem now arose, in how one measures what constitutes a slow attack, which Dr Colvin does not mention in his paper. Twistor59 suggested “time from first instance of 10% max amplitude to first instance of max amplitude”. Assuming sample rate = 44.1kHz for all files, we then measured these – well Twistor did.   I then noticed something – the attack is always a ratio of the total length of sound, or so it appeared to me. Twistor then recorded the length of each sound, and Campermon tabulated it thus –
The test results:table showing duration and attack time

I had proposed that the percentage of total duration of sound in the attack was the important factor. Campermon however found a more useful way to graph this –

As Campermon suggests, there are too few data points and our sample size is too small for this to be meaningful, but our very informal tests show no striking confirmation of the hypotheses that the poltergeist raps have unique or indeed particularly unusual characteristics.  We would like to see larger tests done, with more poltergeist samples included, but remain very grateful to Dr Colvin for his assistance in supplying the wav files these tests.

So what causes the odd waveform?

Campermon in the debate raises some interesting questions –

“One thing that has nagged me from the Colvin paper was this statement from the abstract;

‘Differences in low-frequency wave properties between the two classes of sounds have been noted.’

OK, this has bugged me because in the body of the paper he doesn’t mention much about this. He doesn’t explain in any detail how he treated the recordings, for example, did he filter out the low frequencies only for his analysis? If so, what band of frequencies? Colvin does not make it at all clear, which is one of my original criticisms of the paper.

One explanation for any anomalous low frequency waves observed on the poltergeist recordings may lie in the fact that they were originally recorded on analogue gear and then digitized. Colvin states that he did digitize some himself, but other, digitized sources, were provided by others. Perhaps these recordings suffered from ‘aliasing’? Aliasing occurs in the digitization of a signal when the input signal frequency is higher than the sampling rate. It results in the addition of low frequency signals appearing on the digitized copy. More here; http://en.wikipedia.org/wiki/Aliasing”

Yesterday I hazarded some thoughts on the subject. What was interesting is that all my original experiments had produced, as you can see from my earlier piece and the debate, the characteristic “normal rap” waveform.  However when I recorded my controls, I found some fairly “polt-like” characteristics.

I think two factors are involved, a) the presence of blank wall space that ‘reflects’ the sounds, creating a sustained rise – but I cant be sure that is a factor, I just think it possible b) the transmission of the sounds through two mediums (as demonstrated by the wav file of Lisa bouncing above me through the floor). In most cases my final success in replicating the noises came from hitting an object some distance from the mc stand which rested on my desk – I suspect but do not know that the varying rates of propagation of the sound waves through two different mediums (the air and the desk) led to attenuation of the sound and the waveform characteristic displayed.

This morning just as I was writing this up JG wrote to me describing his experiments on the subject. I am not sure if he intends a more formal publication, but I would very much like to post them on this forum. I have emailed him with details of what we have been up to, and look forward to hearing his thoughts.

Final Thoughts

Assuming I do not have a poltergeist in my basement, or did not use mysterious PK power to alter my recordings ;) I am afraid that at the moment our attempts to test the hypothesis poltergeist raps are in some way anomalous has proven only that they do not appear in a very small sample to stand out: I suspect the raps are perfectly normal sounds, which is NOT to say they are not caused by a poltergeist. Dr Colvin’s hypothesis they are internally generated in the structure of a substance is supported by the recordings; unfortunately they could just as well be an artefact of large bare walls, recording sounds from the other side of a wall, or many other quite normal factors?  Sadly we do not know enough about the conditions in which they were recorded to judge – but further research is clearly required on this fascinating line of inquiry.

Acknowledgements

I’d like to thank firstly and most of all Dr. Barrie Colvin who has offered a quantifiable and fascinating hypothesis, and supplied the four sound files we used; my colleagues in “beer mat parapsychology” and “beer mat physics” Campermon, GrahamH, Twistor59, and everyone who has commented from RationalSkepticism.org, JG for his invaluable comments on this blog, and Becky Smith and Lisa Langood for their tolerance of my loud thumping in the basement and helpful suggestions, and finally Anthony McCann for his hilarious poltergeist rap he composed and recorded to amuse Wendy Cousins and myself!

cj x

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Poltergeist Breakthrough? JSPR publishes Dr Barrie Colvin’s research


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 [2010] 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.

http://www.p-e-g.co.uk/Web/Articles/ART … icle23.htm

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.

http://www.last.fm/music/Okkulte+Stimme … iale+Musik

Schleswig , Switzerland, (1967) taken from a CD.

http://www.last.fm/music/Okkulte+Stimme … iale+Musik

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 –

http://www.channel4.com/programmes/inte … oltergeist

- 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…

Image

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…

cj x

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