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PSI’s
Dave Wood looks into why an annoying feature of most hand-held video and
audio equipment – the Auto Gain Circuit – has ruined the results of many
a paranormal investigation.
I’ve lost count of the number of times I’ve seen it. Be it on
paranormal TV programs or be it on paranormal investigations, everyone
seems to have ‘picked up’ unusual sounds from a dictaphone left alone in
a room or from a video camera ‘locked off’ to record a scene.
Much excitement has resulted from the resulting anomalous noises, even
described by some as ‘electronic voice phenomena’ (EVP). Tragically the
over-active Auto Gain Circuit probably renders many of these ‘results’
as meaningless.
The Auto Gain Circuit was an invention of supposedly thoughtful
developers. The role of the AGC is to keep a consistent level of sound:
when a noise is too loud it ‘turns down’ the volume and when the
environment is silent it turns the volume ‘right up’ in order to try to
record something, anything!
The unfortunate by-product for paranormal investigators is that many of
the sounds picked up during EVP sessions and video ‘lock offs’ are
likely the result of noises which, whilst they sound close, could be
from some distance away. Even the voice of an investigator on a
different floor could be amplified, recorded and heralded as fantastic
‘evidence’.
Professional media recorders have, of course, found ways around these
problems: most of us will have heard producers ‘counting in’ interviews,
not just for timing, but also to ensure they don’t have a ‘noisy’ start
to the interview.
So what should paranormal investigators be
doing to overcome this problem? Generating a constant low level of
background sounds during video ‘lock offs’ may work, as might simply
discounting auditory phenomena in ‘visual’ experiments. The established
practice of using a white noise background during EVP sessions should
also be helpful.
The Auto Gain Circuit is just one possibly confounding factor that
renders much paranormal ‘evidence’ as useless. It’s worth remembering,
also, that using recording equipment with moving parts (such as tape
players or tape-based video recorders) also produce a lot of internal
sounds which are picked up by the microphone.
The best tool in the paranormal investigator’s armoury, as ever, is
rigour; studiously record the environment of any recording environment.
Simply producing a piece of interesting ‘audio footage’ without due care
to confounds and environment doesn’t impress the wider world – and it
should not impress you either!
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