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02/12/2010
EVP Explained
EVP stands for Electronic Voice Phenomena which is
perhaps second only to orbs in being reported as evidence of paranormal
activity. The E part (electronic) describes the device in which the voice (EVP)
is captured on (audio recorder). The most typical type of audio recorder used is
digital over analog (older cassette recorder). “V” of course standing for voice,
although many paranormal research groups and investigators report sounds as “EVP’s”.
Personally, I don’t count sounds as they are not voices and cannot be proven to
have been caused by someone other then those in the room or area. “P” or
phenomena, is the key to it all. The phenomena is in that at the time the
recording occurred, no ghostly response was heard by those present, however it
is on the recording when it is played back from the recorder. It’s really not
that much of a phenomenon as one might think, in most cases.
I have been part of over 70 paranormal investigations
and many research projects. One thing I have noticed is most (not all) of what I
would call true EVP’s are in a very low frequency and/or decibel range. For
example: This EVP captured at the Marsh House on Lafayette, GA is just as it was
captured, no cleaning up or amplifying.
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The Tech. Manager was setting up equipment in an upstairs
bedroom; he was the only person present. He set his EMF detector down on the bed
and was thinking aloud saying to himself, “Where can I set the recorder”
(referring to his digital audio recorder). When he played back the recording,
there was a response that said, “Chair” (he was standing in front of a chair at
the time the recording was made).
In analyzing the recording, here is what we found:
Waveform view of the recording (highlighted in white)
Spectral view of recording
Frequency analysis of recording
The Frequency range for this EVP is 117.88Hz with -47.9
dB. This is an important part of the EVP analysis process because in most
cases, this is where we prove that the voice speaking is not human. The graph
below illustrates human capabilities with regard to speech and hearing, which
may, in some cases, prove that a voice recorded is other than human while at the
same time explaining the phenomena behind EVP’s not having been heard at the
time it was recorded.
With human speech being in a frequency range of approx 400
Hz to just over 4000 Hz, anything lower or higher could not be human. Also
notice that the speech range also bottoms out at 0 dB. Also, anything under 0 dB
is outside of human capability. Let’s look back at the frequency and dB
analysis for the example EVP above. The word “chair” was spoken in a frequency
of 117.88 Hz and dB of -47.9 as depicted in the Frequency Analysis graphic. Both
these figures are well below human capability, but is clearly a voice speaking
the word “Chair”. This is the kind of analysis and data we present with an EVP.
Without such data, we cannot prove to anyone that it wasn’t any of us that spoke
the word or phrase in the EVP.
Notice in the graph above that our speech range is pretty
straight forward, 400 Hz to 4000 Hz across the board. However, our hearing is
much broader (with a curve). This is why we can hear things that are outside of
our speech range such as animals, and sounds other than human speech. Below are
some ranges that help illustrate this curve:
In order to hear at 400 Hz, the decibel (representing
volume) needs to be at least +5. When the sound at that same frequency is +4 or
below we can’t hear it. Although we cannot speak at 250 Hz, we can hear that
frequency if the decibel is approx +17 or higher.
We can hear:
400 Hz at 5 dB or higher
250 Hz at 17 dB or higher
63 Hz at 60 dB or higher
The lower the frequency, the higher the decibel or volume
must be in order for us to hear it on our own.
Since decibel (dB) represents volume, a sound, noise or
voice in a frequency of 63 Hz for example, would have to be very, almost
extremely loud for us to be able to hear it with our ears.
So, that leaves the question, if we cannot hear it how can
the recorder pick it up on recordings. The answer to that is quite simple. Even
though human speech doesn’t go below 400 Hz, other sounds do, so most digital
audio recorders begin recording at a frequency of 20 Hz up to 20,000 Hz. Well
below and above that of human speech.
Once in a while, we do actually hear the EVP as its spoken.
Although it is usually faint, we do hear it. In these cases the EVP is typically
in a higher frequency (above 400) and decibel (above 0) which explains why we
were able to hear it without the aid of the recorders or other equipment.
Even though the analysis can reveal whether the voice
captured is human or not, collecting and listening for EVP’s must be conducted
in a very controlled environment. This can help in eliminating or identifying
any sounds or voices that do occur. Voices you can’t identify by their sound,
are the ones analyzed for frequency and decibel range to determine if it is
human or not.
Probably the single most important rule to consider when
attempting to collect EVP’s is do not whisper. Since most EVP’s are very low
frequency and decibels, they sounds like a human whisper. If you and your team
do not whisper, this makes it a little easier to identify if the voice on the
recording is yours or not.
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