Electronic Voice Phenomenon

Electronic voice phenomenon or EVP is the occurrence of stray, unexpected, or impossible voices when playing back an audio recording. It is believed that the earliest form of voice phenomenon was recorded as early as Alexander Graham Bell when he was experimenting with sound transmission.  EVP experiences have been reported frequently and in many different situations since the invention or recorded media.


The basic belief behind these phenomenons is that they are the voices of spirits manifesting out loud or on recording devices.  Though there are a number of possible explanations for these events, some of them have never been explained scientifically.  On the other hand, there has been no real proof that they are supernatural either.  There are a number of criteria for identification of a true EVP that have become more or less standard.


The first is a class system that defines the quality of the EVP. 

Each anomalous audio clip given a letter to designate its class A, B or C.


A Class “A” EVP is pretty uncommon.  On this class of EVP, the voice is clearly heard and understood.  It also speaks more than a couple words and often seems to be interacting or talking with the people speaking in the recording.


A Class “B” EVP is more common than the Class “A” Clip.  On this class of EVP, words or word patterns can be recognized after reviewing the anomalous clip a couple times.  The words may not be too clear, there is often question about what was actually being said, and the words often have nothing to do with what the other people in the clip are talking about.  Most people will agree however, that there is an actual voice being heard.


A Class “C” EVP is the most questionable class.  The words are usually Garbled, and very hard to understand.  The voice is often very low and mixed in with the background noises making it difficult to hear unless the clip is reviewed over and over again.    Class “C” EVP’s do not usually carry any weight as evidence and many people will doubt that there are any actual voices being heard at all.


There are a number of ways we can make sure an anomalous audio clip is an actual EVP.

Because they are generated electronically, EVP’s often occur on only one device in an area.  Having multiple recorders around can help identify whether the source of the voice is audible or electronic. If it is heard on all the devices, it is may be a false positive, or possibly an Audible Voice Phenomenon.

Investigators will bring attention any stray identifiable sound they make or hear by tagging it so that it can be identified while reviewing the audio.


Only review recordings taken specifically during controlled EVP sessions rather than during the walk through, during interviews, setup, takedown, and breaks.


Plan investigation teams far enough apart so that they do not contaminate each other’s EVP sessions.


Don’t scrutinize too much during review.  If you have to amplify the sound 500% just to hear a garbled voice, it is probably just aliasing in the background noise.  True Class “A” and Decent Class “B” EVP’s don’t really need to be enhanced to be heard, anything else is not worth the effort.


Some people believe that an electronically generated voice will have a limited spectrum of frequencies when compared to a normal human voice.  Others have suggested that Electronic voices occur at lower frequencies than the normal human range, or possibly as a negative frequency (Meaning that the EVP is actually caused by aliasing – which rarely happens on most voice recorders at normal volume)


Some of the theories regarding EVP recordings are:

Electromagnetic fluctuations interfering with or manipulating electronic recording devices. Fluctuations in air flow in voice patterns very close to the microphone of the recording. Manipulation of background noises while they are being recorded to make them sound like a voice.  Vibrations in the area, especially those caused by VLF, ELF and ULF (Very, Extremely and Ultra low frequencies) and Infrasound.


Tests have been done to show that EVP’s can still occur in a faraday cage (which blocks out electromagnetic frequencies).  Though these tests did not specifically prevent other forms of interference from possible affecting the recorder (Air flow, vibrations, outside noises) and are generally dismissed as invalid tests.


There is also some disparity on what methods of recording are most likely to pick up EVP’s. Are High or low ( Frequency Response ) recordings better? Do Anti-aliasing methods reduce the chances of an EVP?  Does noise reduction help or reduce EVP occurrences?  Can voice activated recorders pick up an EVP? What type of Microphone is the best for recording EVP? (Condenser, Dynamic? – Unidirectional, OmniDirectional?) Does white noise tend to produce better EVP quality?  How much audio enhancement is too much to maintain the integrity of the sound?


Given the sensitivity of most recorders and microphones, there is a high probability that what a person thinks is an EVP may just be a noise from the other room or outside the building.  The study of Electronic Voice Phenomenon is field where technology has the potential to do a lot of good, but one where widespread lack of skill and training in the use of the technology can lead to more questions and quite a few false findings.  As with most methods used paranormal investigation, I EVP’s are still experimental, and we cannot recognize them as real evidence until we have fully researched and can understand why and how EVP’s exist in the first place. 


Are Electronic Voice Phenomenon just paranormal myths, or are they reality?  You Decide.