Seán Manchester (from his writings) on E.V.P.:
Electronic voice phenomena (EVP) are recordings of voice or voice-like sounds that are not audible to the human ear. This is also known as instrumental transcommunication which is the collective term for conversing with the world beyond using electronic instrumentation. These instruments can include tape recorders, camcorders, telephones, answer-machines, radios, televisions, or anything else that is electronic. The frequencies of these sounds are usually well below the range of sounds that can be perceived by the human ear. They are usually brief, emitting for the duration of only one word or a short phrase. They are sometimes in a foreign of archaic language. Many are cryptic. Parapsychologist Konstantin Raudive, who popularised the idea of electronic voice phenomena, confirms the emissions as being typically brief, usually the length of a word or short phrase. Konstantin Raudive, a Latvian psychologist who had taught at the University of Uppsala, Sweden, made over one hundred thousand recordings which he described as being communications with discarnate people. Some of these recordings were conducted in an RF-screened laboratory and contained words Raudive said were identifiable. In the 1920s, Thomas Edison told a reporter from theScientific American magazine that he was working on a machine that would be able to contact the dead.
Ever since the invention of electronic recording devices, people have found strange and often eerie voices surfacing on their recordings. Sometimes the voices speak directly to them, despite nobody else being present. Electronic voice phenomena (EVP) is claimed by some to be the voices of souls who have passed on and wish to speak to loved ones left behind. Could this be the case with Juana Chino? Or is it something else, natural or supernatural (demonic), causing the phenomena?
Thomas Edison, when interviewed, stated: "It is possible to construct an apparatus which will be so delicate that if there are personalities in another existence ... this apparatus will at least give them a better opportunity to express themselves." That first device was the electronic recording.
Some will say that all people are hearing in electronic voice phenomenon recordings is random noise filtered through the desire to hear something. Pareidolia is a psychological phenomenon involving a vague and random stimulus, often an image or sound, being mistakenly perceived as recognisable.
We create sounds on the Earthly plane by passing air through our throat and mouth to create the sound frequencies our ears perceive. It has been sought to discover how a non-physical entity can produce the frequencies on tape that we can hear. Perhaps the reason the EVP researchers do not hear the voices directly is because whatever is causing the sounds are having to manipulate existing sound frequencies at the point in the machine where the processing of the analog sound to a digital format for storage is taking place?
Whatever the truth might be about electronic voice phenomena, the jury is still out.