EVP or to give it its full title, Electronic Voice Phenomenon is in essence where a sound is recorded using an, electronic device, VCR, Cassette or Digital Tape Recorder that should not be there and that when replayed sounds like a voice.

No one has yet proven a link between EVP’s and the Paranormal, now there's a challenge handed out if ever there was.

The Argument for and against

To believers in the paranormal these sounds are thought to be made by the voices of Spirits or Ghosts. Sceptics take the view that the recording device has picked up stray RF (Radio Frequency) fields from say a Taxi’s or emergency services radio or nearby TV or Radio Transmitter.

All of these sceptic arguments are at first sight perfectly plausible. Apart from very nearby Taxis and 999 agencies or very powerful TV or Radio transmitters these sources are unlikely to be powerful enough to break through the RF suppression used in AF (Audio Frequency) equipment. This would certainly be the case in the vast majority of locations and with half decent equipment.

All AF audio components do indeed have some sensitivity to RF, although there still has to be some fault present for an RF signal of greater than 30 MHz to be demodulated back into audio. Another problem I would cite is that modern transmissions are FM (Frequency Modulated) as opposed to the original proposition for this cause which was AM (Amplitude modulated). There is a case for AM signal breakthrough, but FM as a transmission method was deliberately brought in to limit interference with other equipment.

I have recently heard of mobile phones being cited as a potential EVP cause, this is completely ridiculous and absurd in the extreme. The reasons for my complete dismissal are that Mobile Phones use even higher frequencies, many hundreds of MHz in fact. Add to this that the fact that the transmission is also digitised prior to transmission and you can see that there is a huge hole in this version of the theory.

I am fully prepared to accept that analogue transmission could break through if there is a fault in the audio equipment or if it is badly designed, but adding to this a suggestion that the receiver could decipher the digitised signals as well is stretching things far too far.

I have also come across another attribution for the phenomena based on the use of those, plug into the mains, baby listeners or intercoms. This is a much more valid call. There is probably a greater likelihood of RF break through due to the very poor RF screening applied to most recording appliances at the mains input.

This does not however explain why battery powered equipment should be affected. Receiving RF to any great degree, enough to cause breakthrough, requires some form of earth. Your hand in contact with the equipment could perform the role of a suitable earth in some cases. Leaving a battery powered recorder on a wooden table would though would eliminate the chance of this being a factor in all but very extreme cases. The moral of this is don’t try recording EVP’s in an old cottage that is built right next door to a Radio or TV Transmitter or the local taxi office etc. It’s unlikely that breakthrough will occur, but if you can eliminate this as a potential cause you should.

I think there is a larger argument in favour of EVP as far as the words and phrases that are recorded are concerned. Some of the words that I have heard could for example be contained in a radio play, but why is there no recorded music, inane DJ’s or commercial adverts? Why are only voices picked up, it’s a sobering thought! I have been recording at haunted locations for a while now and I do not eliminate anything that I can hear, so why do I not hear music or DJ jabber?

Before Digital recorders came into existence it was believed by psychics and believers that spirits could directly imprint their voices onto the magnetic tape used in the old heavy valve equipment of earlier years. The evolution of digital recorders into inexpensive and highly portable devices has shown that EVP’s can also be digitally recorded. To be honest I never understood how a ghost could know how much tape would need to go past the recording head in one second to make the sound audible anyway.

The use of digital recording dispels and removes another theory of how EVP’s may occur, that of the reused audio tape. While this at first sight looks like sceptics nit picking, this is a perfectly valid potential cause. Audio tapes never run completely straight every time they are used, particularly if different recorders are involved. Hence there is no reason to suspect the recording at a haunted location will completely overwrite a previous recording of say a radio play. What you might in fact get is a small break in of the odd word or phrase, one very good reason to avoid reusing audio tapes if you are hunting EVP’s.

What does and EVP Sound Like

Some of the alleged EVP sounds that are recorded fall outside the normal hearing range, but are well within a range that can be picked up by a microphone. If a microphone can pick up a sound it can be recorded on a portable audio recorder. Almost always anyone present in the area when an EVP is recorded will hear absolutely nothing at all. This has given rise to the belief that spirits can directly affect electronic recording devices in some way. Personally I think the reason nothing is heard is that EVP’s are invariably quiet and simply pass unnoticed as background noise.

An EVP may sound tinny or have a pronounced echo, whistles or pops. Voices can often sound odd almost mechanical sometimes making it difficult to sex the speaker. In my experience the voices recorded are almost always quiet, often whispered and seem to have an odd hollow echo like quality. This makes them not only hard to identify if there is a lot of background noise or people talking but also hard to understand.

When replayed the recorded sounds can sometimes be heard easily, these are usually classified as class A EVP’s, which are the rarer. In a number of years of EVP recording I have never managed an EVP that can be heard without some form of enhancement processing. If you just have to amplify the sound to hear it, but it is otherwise clear and easily understood it is still a class A. Class B by the way is more difficult to hear but can be heard and understood with difficulty by most people. Class C EVP’s can be heard but not distinct enough to be intelligible. Personally I disregard class C EVP’s

For the majority of EVP’s some form of digital processing is needed in order to aid hearing. This usually takes the form of amplification or manipulation to hush the background noise and so enhance the prominence of the recorded EVP. We will discuss the methods of doing this in more detail a little later

A few Important Facts about RF and Human Hearing

Let’s first try to understand a few potted facts about RF and human hearing.

The normally accepted frequency of the human voice is about 300 to 3,000 Hz, this statement is generalised and over simplified because the harmonic frequencies are being ignored. In fact, the human voice ranges from around 20 Hz to about 14,000 Hz when harmonics are included.

Most voice energy is concentrated below 1,000 Hz. Vowels have most of their energy below 1,000 Hz. Consonants have most of their energy above 1,000 Hz. Harmonics in a voice go above 3,500 Hz. The frequencies which appear to have the most significance for human speech lay between about 100 Hz and 4,000 Hz. Note this latter point for when you are processing EVP’s

The range of frequencies that young, healthy adults can hear is between about 20 Hz to about 14,000 Hz (some up to 20,000 Hz), but we perceive speech mainly in the frequency range of 500 Hz to 3000 Hz. Older people or those with damaged hearing, sadly I am now beginning to fit into both categories, may have problems resolving any sound frequencies much above 8,000 Hz.

Compare this with the Dog Hearing Frequency Range of about 50 to 45,000 Hz, Cat’s Hearing Frequency Range of about 45 to 85,000 Hz and you will see just how primitive human hearing is.

Most sound recorders can easily record sounds up to 30,000 Hz, some as high as 40,000 Hz. This is approaching ultrasonic frequencies. Most Dictaphone type Digital recorders are designed to ignore any sounds over 18,000 Hz

Sounds which the human ear can hear range from 0 dB (so faint that only the best hearing person can hear them) through to a painful 180 dB (as loud as a rocket taking off). Typically we speak in the 45 to 60 dB range.

In the UK, AM radio uses frequencies between about 18,000 Hz and 1.6 MHz (1, 600, 00 Hz), FM radio ranges from 88 to 108 MHz, and TV ranges from 470 to 854 MHz.

Cellular mobile phone services operate within the frequency ranges 872 to 960 MHz and 1,710 to 1,875 MHz.

Waves at higher frequencies but within the RF region, up to around 60 GHz, are referred to as microwaves and have a wide variety of uses. These include radar, telecommunications links, satellite communications, weather observations and medical diathermy; intense sources of 2.45 GHz microwaves confined within ovens are used for cooking.

1 KHz = 1,000 Hz, 1 MHz = 1,000,000 Hz, 1 GHz = 1,000,000,000 Hz

Recording EVP’s

This can be as simple or as complicated as you wish to make it. It can also just as easily cost next to nothing or a fortune its up to you.

Personally I hate spending money, after all you have worked hard for it, well I have. Call me scrooge if you like but at least I have an excuse for being tight.

My favourite recording weapon of choice is an Olympus VN-480PC Digital recorder. These can be expensive, but shop around and you will find that some places sell them at half the price, mine cost just £49.95, list price at the time £89.95. While there is an internal microphone it’s not great and it’s certainly not good enough for EVP use. Neither is the lapel microphone also supplied as standard. I use a small cheap and nasty boundary microphone cost £2.99 from Maplin. The only downside or upside, it depends on your point of view, is that it can hear a pin drop some distance away in any direction. More expensive versions of these exist, but I have not experimented with them so I cannot advise on the pros and cons.

The alternative to boundary microphones are the directional types, these can pickup sound from between 45 and 90 degrees depending upon type and spec. Also available at a price are the parabolic microphones, these are the holy grail of directional and they can hear over long distances in a very narrow beam. I am not convinced of the value of these for gathering EVP’s.

This brings us to the next important point how to use your equipment. Firstly DO NOT use the LP setting on your digital recorder if it has one. To increase the recording time LP uses a more drastic compression algorithm which will cut down on the sound frequencies recorded and that’s not good where EVP’s are concerned. If the reason you are using LP is that you don’t have enough recording capacity either buy a unit with more memory, use it only when you need to or have a laptop to regularly download it on to.

Another thing to avoid is the use of any sound based automatic recording start feature. EVP’s are by their nature very quiet and if you use this feature unless the trigger is exceptionally sensitive, you will almost certainly miss out on anything quiet.

If your recorder has a date time feature, the Olympus does, make sure you set it accurately. Use the GMT time signal and make sure any other equipment on site is likewise set. If something kicks off you will be able to listen to it using all of the equipment on site, all with the same timeline. This has proved invaluable to me many occasions during investigations, but it’s often overlooked in the excitement of getting ready for an investigation. Personally I have a pre investigation check list and after changing non rechargeable and charging up all of the rechargeable batteries comes setting the clocks.

Do not try to record EVP’s in areas where there are likely to be background voices, in a building off the high street around pub closing time is a really bad idea! Also be conscious of how noise may enter your chosen room, look out for vents, open windows, partition walls, fire places etc. It’s so easy to get caught out if you don’t look.

Make the rest of your team aware that you are going to try for EVP’s and get them to stay quiet or move far enough away from the area where you are working. If you are staying in the room while recording find a place away from the microphone where you can sit comfortably, any movements you make will be recorded and will appear in your evidence. Try and use a cushion stay as still as possible and be mindful of creaky floorboards.

I have two modes of operation that I use. One is to use a prepared list of questions that I read out leaving a gap for an EVP answer. Start by introducing yourself and say why you are there and what you are expecting any spirits present to do. Read your question slowly and speak clearly, personally I leave 10 seconds between questions for an answer. Count slowly to ten by saying the number followed by the word thousand and you will take around 10 seconds. At the end say thank you, you may sound daft particularly if you are a sceptic, but you never know who or what else may be there in the darkness.

I suggest that write your questions before you go to the location, things like what is your name, how old are you, did you die here, what year did you die, how did you die, did you live here (work here) etc are all good starting points. If you know something of the sites history you can ask targeted questions, but keep any knowledge of the location out of range of your sensitive's or you may spoil the investigation for your team.

My second mode of operation is to leave the recorded in an empty room. Often I also leave an IR alarm in the room as well to prove that there has been no interference, accidental or otherwise. Make sure before you leave the room you say who you are, what room the recording is in and the time and do the same when you return to retrieve your recorder.

You can also have the recorder running in a vigil if everyone is sitting quietly. If people are in the room besides stating the time and the location get everyone who is there to say who they are. If there is any doubt later about voices on the recording being from the team this will usually settle the debate.

If people are taking photographs in the room ask them to turn off the bleep sounds if possible or get them to say flash just before they do. This is good paranormal investigation manners anyway. Recently I found what I thought were sneezes on a recording, this was interesting until I discovered that is was caused by a camera phone. It’s easy even for relative experts to get caught out sometimes.

Enhancing your EVP

It is important here to stress the need to keep a virgin original copy of your recording and only to enhance or process a copy of this. There are two very good reasons why this is a good idea. First if you come out of the processing with something spectacular, then you can give a copy of the unedited version to someone else in order for it to be authenticated. Secondly if you over cook your editing you can start again from a copy of the original.

While almost all audio editing software has an undo capability it often only affects the last change you made and it may not be that one you now need to undo. Unlike analogue recordings digital recordings are exact copies and can thus be reproduced any number of times without loosing quality. Always make your copies on a computer using the operating system, Windows or Mac, file copy functions

There are a great number of computer applications available for audio editing; some of these are hideously expensive. My advice is forget the expensive and for the most part the free software. I should add that cost or lack of it is absolutely no guarantee of quality, merely a reflection of the area of the market that it is aimed at.

There are plenty of very good examples of good middle of the road audio processing software available and you do not need to part with large sums of money to get a good one. Personally I like and use Acoustica, which is available for download on the internet from Acorn Digital Media. Another useful piece of software to have is ExtractAudio. Acoustica and other software like it can only edit audio files, but what if your EVP is on the soundtrack of a video, this is where ExtractAudio comes in. This is a neat little utility that can extract the audio track off the video into an audio format file that you can process with Acoustica.

So more importantly what is the spec for a good audio editing software package, what should you look for?

Well for me you absolutely have to have a graphic readout showing the sound waveform, preferably this should be able to handle stereo. Personally I do not use stereo recorders, but it does come in useful from time to time. I use the graph to show me where to start looking. Initially you will not be able to do this, but as you get more experienced you will find that you can often see where an EVP may be. Just don’t ask me how I know where to look it’s an instinct thing.

Where the graph comes into its own is where you can see loud noises its likely to be pointless looking there.

Another vital feature is the ability to zoom into the wave form, to visually amplify the sounds if you like. This lets you see the quiet sounds while allowing the load sounds go off the scale. This does not alter the playing volume but does give you a visual edge.

Your audio processing tool also needs to have a good electronic graphic equaliser. This is used to filter out some sound frequencies or reduce the louder sounds so that you can hear your underlying EVP more clearly. Acoustica has a particularly flexible if sometimes rather fiddly variety, allowing you to apply quite sharp filtration of very specific frequencies.

The ability to make a change and hear it in preview without saving the change is an important and very useful feature.

Some packages like Acoustica also feature a predictive/adaptive noise suppression facility, carefully used this can be a great tool, but the key word is carefully! You can control the degree of suppression, too much and you can loose your EVP completely or worse still change an explainable voice into a Darlek. Start with a little and cancel or undo the change if it’s not enough, then turn up the dial and try again. It is when doing this that a preview feature is a great asset.

One feature that I find particularly useful is the ability to highlight a section of a track and to repeatedly replay that section. I often do this to decide if its worth doing any other processing.

One of the most important and most commonly found features is the ability to select a piece of the track to amplify just that selected section. This allows you to hear the quiet whispers, but there is no gain without pain, no pun intended. When you amplify the sound you do exactly the same to the noise, so rarely can you just do one edit. What follows becomes a sort of recipe of a bit of this and a bit of that. All you can do is try it and see, if you mess up, simply go back to your original copy.

Almost all editing software will let you cut out sections of the audio track, which is how you save your individual EVP’s when you have finished processing them. On point here the fact that you can cut from the track you can also paste, doing this is changing the recording and is simply not on if you want to stay credible.

At this point it is worth mentioning that while attempting to clean up a faint recording it is very important not to do too much manipulation, cleaning up the noise and increasing the volume is ok, it is not fundamentally changing the recording. I personally have big issues with increasing or decreasing the recording speed or the frequency of the recording. I may occasionally alter the speed “a little” but it MUST only be a slight change to aid hearing any more than that is a complete taboo.

Big non starters for me are things like reversing the recording. Those of you who are of a more mature age may remember a famous court case around a Black Sabbath album, relatively innocuous lyrics when played backwards in places appeared to encourage demonic worship and killing. I rest my case!

Listening to EVP’s

I have read differing accounts of what’s best and I think that there is a certain degree of personal preference here.

So when listening out for EVP’s what’s best big HiFi speakers or headphones? Believe it of not I have found that the best for me is the cheapest nastiest pair of amplified PC speakers you can find, the more tinny the sound the better. You need the volume up a fair way, so it’s best if you are alone in the house, have the windows closed and have very understanding neighbours. Don’t try to listen to hours and hours of recordings your ears and brain get tied quite quickly, half hour chunks with a similar length break between are best. I also find that having a blank mind works best, don’t listen intently for every change of sound, if there is a voice there you will notice it anyway.

Ok so you have recorded, found and enhanced your EVP, but what is being said? This is where your problems really start. You may well here “Hello” but if you play this same EVP to another person they may hear something completely different.

If you tell your listener in advance that your EVP is saying hello they will almost always hear the same thing. This is a kind of auto suggestion where the brain is being primed to expect a result and actually makes the sound fit what they are expecting. This is a good thing to experiment with it works almost all of the time, although you will occasionally find some people on whom it does not.

It has also been suggested that what you hear even without auto suggestion will depend on your beliefs, what you have recently been doing and whether you have a suggestible nature. It’s an interesting theory.

A better approach when playing EVP’s to other people and one which I use is to just play the EVP without telling them what you have heard. Try this on a number of people to canvass opinion. Personally I find this very enjoyable, because you usually get a variety of answers, some very different from what you heard. Even stranger if you play the same EVP a bit later to the same person, but tell them first what you think it says, this being different to what they heard last time, you can actually make them hear what you say it is. Enough said.

What I tend to do is to ask a number of people what the EVP is saying and use the answer that most people hear. If I get 20 different answers from 20 people then sadly I do not attribute what is being said, leaving it up to the listener. This represents a rather typical lower class B although I call it a class C EVP. If they all agree and it’s clear then we have the Holy Grail class A, but don’t get your hopes up. If I get enough answers that say the same thing and the EVP is fairly clear that is a class B.

If you get unexpected sounds on your recording make contact with your host and ask them about the sound. If its happened before they will likely have heard it. There was one recording I did a while back where an empty room had the sound of what could have been caged birds. I asked the host and he pointed out brightly lit electricity substation down the road. The bright lighting makes the birds active in the area and unusually they sing at night, drat. This illustrates how easy it can be to make a fool of yourself and how easy it is to avoid that fate.

Conclusion

If you take all of the above on board as a starting point you will not go far wrong, the rest is all down to experience. Have a go and if you do not get results straight away keep trying, with practice you will.

Appendix

Here is an example of a stereo Acoustica Waveform, showing amplified sound going off the scale and revealing the quieter sounds beneath. The sounds to the right are the aftermath from the team present reacting to a dragging sound.

Below a real EVP from an investigation before it was amplified, you can see the waveform is flatter to the left, this is the background sound. This illustrates my point that you can use the wave view to isolate sections to view.

Below is the same section as above, but with a *100 visual zoom applied. The section of EVP speech can now clearly be seen.

Below is the final EVP, recorded during an investigation vigil, click it and have a listen. I am not going to tell you what we think it says, see what you think!

Below you can see the Olympus VN-480PC Digital recorder and Boundary Microphone that recorded this

 

Below is a sneak peak at ExtractAudio, used to drag audio off of a video soundtrack

Written by Colin Jordan

*Colin is an IT Professional currently working for a Blue Chip Company. He has worked in the computer industry at many different levels for the last 26 years. During this time he has submitted many papers for professional publication as well as part of his day to day professional career.

Colin has had a long term practical and theoretical interest in Radio and Electronics. In his teens he frequently wrote articles for magazines, some of these by commission, and is now a Committee member, Equipment Specialist & Field Investigator for CASPIR UK and has Co Founded his own website/group TCPI. Whilst open minded, Colin remains at all times a hard to convince sceptic.*

© County Society for Paranormal Investigation and Research - 2008

 

Last Updated 27/07/2008