Since its independent (and arguable) discovery in 1959 by Friedrich Jurgenson in Sweden and Attila Von Szalay in the US, EVP (Electronic Voice Phenomenon) has grown to be the biggest tool used (and misused) by paranormal teams across the globe.
In the early years of experimentation, a greater degree of success was achieved when stochastic resonance was employed to amplify the signal. Generally, this was in the form of background 'white noise'. But these days, one would be hard-pressed to find any team doing this.
What happened to the work of these pioneers?
I have a clue, but I'll keep an open mind for the moment.
It seems that most people these days view (consciously or otherwise) the whole ghost hunting / paranormal investigation meme as having manifested over the past decade with the advent of several reality programs on basic cable. But for many of you, the truth is entirely different.
In reading an account in a book of mine about a ghostly voice recorded on tape, a Maryland-based paranormal team was mentioned and it struck me that this was around 1986, decades before the dawn of Ghost Hunters. Furthermore, when I researched topics for my book, I often stumbled across various psychical groups and ghost hunting assemblies with lofty sounding names dating back decades earlier.
We sometimes forget that there have been trailblazers and mavericks (no, not the vehicles) on the paranormal path for many years. They did some groundbreaking work, experimenting with equipment and methods, trying out new hypotheses and discarding things that didn't work.
Was that the case with stochastic resonance in EVP experimentation? Or is it that after a while, when the guides and how-to's started coming out, and then the television shows, people just became lazy. We went from eager minds and learned men to the disciples of Ghost Hunting For Dummies.
So, remember in doing your own research to actually do some research. Learn from others besides those on TV and be willing to throw out anything. This field is wide-open; there are no set laws. If break-throughs are to be made, it will be by the intelligent-minded mavericks who put more effort into research than into promoting their team.