"I have been at work for some time building an apparatus to see if it is possible for personalities which have left this earth to communicate with us."

Thomas Edison, 1920

What if you nonchalantly recorded something around your house, let's say a music practice session. Then when you played it back, you clearly hear someone whispering. You didn't hear it when you recorded it, so what was it? If you were playing back a video you shot and you heard a distinct voice that wasn't there when you were recording, would you think this was a ghost? Something from another time or dimension? Recording anomalies? Someone playing tricks on you?

Many unfamiliar sounds throughout history can be attributed to nature, machinery, and even hoaxes. As our post-industrial society grows, so does the list of unexplained sounds, like trumpet sounds from the sky, humming cities, and ocean whistles. The proliferation of audio and video technology has generated its own tally of the strange. Specifically, weird voices that have been inadvertently and unknowingly captured. These recordings and transmissions sound eerie but have a very unsexy-sounding name: "Electronic Voice Phenomenon," or EVP.

I'm going to try to be nonjudgemental while exploring EVPs because I have seen and heard things that I can't explain. Like Fox Mulder, I want to believe. I'll let you be the judge after I take a hard, cold look at some of these. Many documented EVP recordings have been part of ghost, afterlife, or supernatural research. Early attempts at using record cutting recorders for psychical research of voices were unsuccessful. When reel-to-reel recorders came along in the 1950s, researchers such as Attila von Szalay and Raymond Bayless claimed success after controlled experiments. In 1959, von Szalay wrote in the Journal of the American Society for Psychical Research that voices not heard during recording but on playback said, "Merry Christmas and Happy New Year to you all." That same year, filmmaker Friedrich Jürgenson was recording birdsongs. Upon playback he heard his dead father and late wife talking on the recording. Watch the video of Jürgenson playing his tapes here.

I have to admit that Jürgenson's tape is pretty creepy. But let's examine possible explanations for the voices heard on von Szalay and Jürgenson's tapes. For one, they were recorded in the infancy of modern magnetic recording. Many of these recorders were subject to stray radio frequency (RF) and magnetic interference., especially if consumer-level microphones and cabling were used. Can we be sure that the tape they used was virgin, unrecorded stock? Because tape was expensive in the 1950s, it was often reused. If it had been recorded on before, then it's possible the old recording was not completely erased. It could also be mechanical problems with the recorder. Sometimes tape will stick or fold onto itself. The dragging motion while playing can cause squealing and other sounds. Another possibility is the limitations of the recording technology itself. Magnetic tape exhibits hiss, wow, and flutter. A combination of these could create phantom frequencies, which have regularly dogged audio engineers when mixing multiple sounds together. The birds, background ambience, hiss, wow, flutter, tape drag, and RF could have all converged for the perfect storm - err - whisper. And finally, von Szalay was trying to record unheard spirit voices. He was motivated to hear something - anything. In Jürgenson's case, perhaps he experienced auditory pareidolia from longing for his deceased family.

Now that digital recorders are the norm, some of those technical arguments don't enter into the picture. But handheld digital recorders are susceptible to RF, hiss, dropouts, data corruption, and can suffer when batteries are low. Built-in microphones are notoriously lower quality. In light of these potential problems, researchers try to take precautions by recording in environments with RF and acoustic shielding. Some have even tried to build specialized equipment to capture unheard voices, but they require a cryptic mental connection between the researcher and the apparatus. Despite the negative perception of EVPs, there have been serious, but inconclusive, studies. Most of the research concludes that EVPs are probably a result of technology quirks or subjective listening.

Or maybe not. Examples of EVPs from earnest people keep showing up. It's fun to think that perhaps dear late Aunt Sally may be trying to communicate with us from beyond. What would she be trying to tell us? What nugget of wisdom from the afterlife does she have for us? Maybe she would say: "Don't believe everything you hear."

Tags: ghosts, Thomas Edison, "EVP"