http://theshadowlands.net/ghostwav.htm
EVP is a way to communicate with spirits. Researchers believe that the voices of the dead can be recorded and played back on magnetic audio tape. It is the most modern way to communicate with the spirit world. Some skeptics believe that they are not voices of the dead but radio or CB transmissions.
It has been said that Thomas Edison was working on an EVP device. However the credit for discovering EVP goes to Fredrich Jurgenson when he was recording bird sonds in the Sweedish countryside and on play back he distinctly heard the voice of a man discussing nocturnal bird songs in Norwegian. He had heard nothing during the recording but many voices on playback, some giving him instructions on how to record more voices. EVPs are also called Raudive Voices after Konstantine Raudive who recorded 100,000 voices. He published "The Inaudible Made Audible". EVP research is done all over the world but most heavily in the United States and Germany. The Association for Voice Taping Research was founded in the 1970's in Germany, and American Association - Electronic Voice Phenomenon in 1982. Conferences are conducted world wide by engineers and electronics experts who devise special sophisticated equipment to record EVPs.