The Science of an EVP

There you are, the only one in the house. Nervously in the dark you clutch your tape recorder and ask a question. Your ears hear nothing, you begin to relax and ask a few more questions. Still nothing. You decide to take a break and play the recording back. You sit in the dark straining to listen to the silence between questions half hoping you catch something, afraid that you actually might. Then you hear it. An answer. It sends chills down your spine. You check the house one more time, you search outside up and down, and you find nobody. You’ve just recorded an EVP or “Electronic Voice Phenomenon.”

What exactly is an EVP. The common answer is voices of spirits trying to communicate. But, that could be a rather harsh conclusion. There are many things that could cause voices on digital or tape recorders. Only after looking at the context of the EVP itself can you draw any conclusions as to what could have caused it. To really get to the bottom of EVPs we have to first examine all the things that can potentially cause one to show up in your recordings. But, before we even get to the paranormal causes, let’s discuss the things we know for a fact will cause voices to appear in the dead space of a recording.

Radio Transmissions are often picked up by and digital or RF device. Have you ever been talking on the phone and you start to hear another person’s conversation? Or, if you have ever been listening to the radio, and suddenly you can hear radio chatter from the police or air-traffic bleed into the broadcast. These are the most common examples of Radio Transmission contamination. While it is impossible to prove that all EVPs are due to natural phenomena, skeptics maintain that they are probably due to such things as interference from a nearby CB operator, cross modulation, or ionospheric ducting. Given all the voices being transmitted these days by cell phones, AM and FM radios, TVs, baby monitors, walkie talkies, shortwave transmitters, etc., it isn't strange that unexpected voices should be heard now and then on our electronic equipment. I've picked up CB transmissions on my VCR and my neighbor's voice from her cordless phone on a baby monitor. Some of the "voices" are most likely people creating meaning out of random noise, a kind of auditory pareidolia or apophenia. And now that the phenomenon has a number of devoted followers (thanks in part to the movie "White Noise"), some hoaxers have probably entered the fray.

Just like a radio, digital recorders will intercept stray radio frequencies that broadcast through an area. If you happen to be in a structure containing allot of metal framework, or siding, it can act as a conductor for the signals. Since the device you are using is designed to transmit audio, sometimes the result can be a ghosted voice that seemingly comes from nothing. The same thing can happen on a magnetic strip tape recorder (such as a classic cassette recorder or reel-to-reel) many times it will be more clear. Since the technology actually uses a magnet to record, it gets a more defined imprint of the audio. Given that this is such a commonly document occurrence, it’s hard to ever prove that this method could provide any reliable results. But, there are a few things that can be noted. Although this has been documented to happen, there is not a whole lot of hard data to back up exactly “how” this happens. There is allot of argument over if recorded EVPs are electromagnetic or acoustic. The signatures on a fine number of EVPs would suggest neither (these are the ones that we would call credible.) But, the ones which obviously fall into the other categories typically fall into a range of recorded between 300 – 4200Hz range which falls perfectly in line with radio and TV broadcast.

One of the other common culprits grounded in reality is sub-conscious contamination. It’s estimated that one in every three people will sub-consciously talk to themselves to fill silence and not even be aware that they did it. In several studies the frequency of this happening increased when the subject was asked to over a period of time consciously ask questions to an empty room. The people doing the study notated every time the subject would whisper, make a noise, or make any kind of audio contamination. When the tapes were played back for the subject and they would hear voices or noises (responses) to their questions, 7 out of 10 times the subject would swear they did not make the noises heard on the tape until the video footage was played back for them. The conclusion of the experiment was that most EVPs are actually caused by audio contamination of the people recording them. However, there is a tell-tale sign when this is the case; Audio contamination caused by a human voice will always fall within a decibel range of 45 – 60 dB, and within 20 Hz to about 14,000 Hz. Anything above or below those levels cannot be produced by the human vocal cords and often not even registered by human hearing.

Another great explanation that deserves allot of weight is the idea that many EVPs are the result of auditory pareidolia or apophenia. This is our brain trying to make sense of random sounds. Psycologist Jim Alcock explains the idea “Perception is a very complex process, and when our brains try to find patterns, they are guided in part by what we expect to hear. If you are trying to hear your friend while conversing in a noisy room, your brain automatically takes snippets of sound and compares them against possible corresponding words, and guided by context, we can often “hear” more clearly than the sound patterns reaching our ears could account for. Indeed, it is relatively easy to demonstrate in a psychology laboratory that people can readily come to hear “clearly” even very muffled voices, so long as they have a printed version in front of them that tells them what words are being spoken. The brain puts together the visual cue and the auditory input, and we actually “hear” what we are informed is being said, even though without that information, we could discern nothing. Going one step further, and we can demonstrate that people can clearly “hear” voices and words not just in the context of muddled voices, but in a pattern of white noise, a pattern in which there are no voices or words at all. Given that we can routinely demonstrate this effect, it is only parsimonious to suggest that what people hear with EVP is also the product of their own brains, and their expectations, rather than the voices of the dearly departed.” Since the actual process and result can be duplicated time and time again, we can conclude that the phenomenon is a genuinely a scientific explanation for a percentage of what we identify as EVP. After all it should go to note that the majority of people who find EVP evidence we’re looking for it in the first place. Typically, people will not notice an out of place voice in their recordings unless they were actually trying to find them.

To add to this idea, Sound Engineer David Federlein thinks: “it is safe to say that unless the EVP believer is highly bankrolled, I use much higher standard recording equipment, built to much higher tolerances. That being said, I've never heard from the dead, and I have been listening to tape and hard disk recordings for years. It may be the low quality of their equipment that is cause for mistaken ghosts, but it sure isn't lack of willed ignorance!

For example one website says to set the "sensitivity level" of the microphone to the highest possible setting as ghosts are apparently afflicted with laryngitis. Doing this raises what's called the "noise floor" - the electrical noise created by all electrical devices - creating white noise. If I were to filter white noise (the audible equivalent of watching the snow on a detuned TV) I could make it say just about anything. This is really no different than using a wah pedal on a guitar. It's a very focused sweep filter moving about the spectrum creating open vowel sounds. Was Peter Frampton channeling? I hardly think so, however his use of the "talkbox" effect on his guitar sounds exactly like some of these recordings. When you factor in other aspects of physics, such as cross modulation of radio stations or faulty ground loops in equipment, you have a lot of people thinking they are listening to ghosts when in fact it is nothing more than a controlled misuse of electronics. (Personal correspondence).”

Federlein finds the website particularly amusing with its list of 17 helpful tips for the ghost hunter including using brand name tapes and maintaining a positive attitude. But nothing is said about using high quality electronic equipment.

“I can't stop laughing at the suggestions given on one site that you should act like you know there's a ghost there at all times. Is that how to get them to be more responsive? Are we to really believe that ghosts won't actually talk to us because we aren't acting cool enough? Perhaps we should set out a plate of cookies.”

While not particularly fond of his snarky comments about trying to stay positive, I tend to agree about his view on equipment. While my group happens to have access to very high end recording equipment, many do not.

But, lets for a moment look at the other side of that argument. It’s not fair to write off all EVPs as electrical interference. From the AA-EVP Archive longtime researcher Bill Weisensale’s response to concerns expressed by Dr Karlis Osis, with the American Society for Psychical Research, about eliminating mundane causes for EVP.

In early 1975 … the controversy was still raging as to whether EVP voices arrived via acoustical or electromagnetic means. (It is generally accepted now that neither is the case.) At the time this was most perplexing. It seemed reasonable to believe that if EVP arrived by electromagnetic signal, a radio receiver would be required in all cases, and yet some methods did not involve any form of radio receiver. Conversely, if they were of an acoustic nature, then all methods would, of necessity, require the use of a microphone, and yet there were some methods that do not involve a microphone.

I reasoned either the voices had to be both acoustic and electromagnetic, depending upon the method of recording, which seemed very unlikely, or they had to arrive by some other kind of energy, which was of neither electromagnetic nor acoustic in nature. (We have come to call this PK energy, for lack of a better explanation.) In order to find out which was the case, I used a (steel) 50 gallon drum with a removable lid …

I brought the drum into the house, laid it on its side on a wooden pallet, and blocked the sides to prevent it from rolling. Next, very small holes were drilled in the drum and lid. A piece of heavy wire, with a solder terminal, was then bolted to the drum and run out through a window where another solder terminal and bolt were used to attach the wire to a steel stake driven into the ground. A second wire and solder terminal was attached to the lid and soldered to the first wire. All connections, drum to wire, lid to wire, wire to wire, and stake to wire, were checked with an ohmmeter to ensure there was no resistance and everything was properly grounded. Before doing the experiments, water was poured around the steel stake to ensure proper grounding.

In the initial experiment, which was to check the efficiency of the shield, a battery powered radio receiver was tuned to a strong station, the volume set rather high, and placed inside he drum. A battery powered tape recorder was then connected via patch cord to the radio, also placed inside the drum and the lid bolted into place for several minutes.

Upon removing the recorder and reviewing the tape, it was found that the station was quite clear with the lid off, but when the lid was bolted into place, the station totally disappeared and its presence could no longer be discerned even with the closest listening. We then adjusted the radio to between station static, listening carefully to be sure there were no distant stations present, placed the radio in the drum with the recorder and made several recordings with the lid bolted in place each time.

We found the voices appeared inside of the shield just as they did with no shielding. Also, since the radio and recorder were connected via patch cord and there was therefore no microphone involved, this experiment eliminated (to at least my own satisfaction) both the acoustic and the electromagnetic hypotheses.

What does this all boil down to? That with all of the above considerations for false EVP’s when the contamination variables were nullified, EVPs were still on occasion captured. Meaning that while the great majority of EVPs presented as evidence, some can still be proven as a valid unexplainable phenomenon.

What that phenomenon is remains to be debated. The most common theory being spirits. But when there is no explanation to be had you cannot rule out extra dimensional beings, aliens, or other such things. Even the theory that our species at some point in the future learns to harness the tachyon particles to carry radio frequency backwards through time. We could be potentially receiving broadcasts from another point in time.

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