What is EVP ?

Wikipedia. Says :
Electronic voice phenomena (EVP) are sections of static noise on the radio or electronic recording media that are interpreted by paranormal investigators as voices speaking words usually attributed to ghosts or spirits.[1] Recording EVP has become a technique of those who attempt to contact the souls of dead loved ones or during ghost hunting activities. In addition to deceased spirits, various paranormal investigators say that EVP could be due to psychic echoes from the past, psychokinesis unconsciously produced by living people, and the thoughts of aliens.

[http://www.ghostpix.com] Say's :

E.V.P stands for Electronic Voice Phenomena. This Phenomena occurs when the voices of a Spirit interrupt an Electro Magnetic Field,"E.M.F's", so inturn using audio tape i.e. from a micro cassette recorder reveals these voices where as before they could not be heard by a human ear. It is the same way with a dog-whistle, the dog in this case being the audio recorder. We as humans cannot pick up the sound of this dog-whistle because the frequency is to high. The dog, on the other hand can, because its ear drum is designed for hearing higher frequencies. The audio recorder uses magnets to record onto tape when an Electro Magnetic field is interrupted such as when paranormal activity occurs. This inturn effects the tape i.e."E.V.P"
electronic-voice-phenomena.net Says :
Electronic voice phenomenon or EVP for short is quite basically voices and other utterances that appear on audiotape and digital media without the person/s being aware of it at the time the recording was taking place. In most examples of EVP, the voice or voices only speak a few words and some of the voices can be very distinct and yet others hardly coherent at all.
Electronic voice phenomena came to light in 1959 when the Swedish filmmaker Friedrich Juergenson unwittingly captured voices on audiotape. After recording birdsong in a forest, Juergenson discovered on playback that there was a distinct male voice remarking about birdsong at night! Listening carefully, Juergenson also heard the voice of his deceased Mother! After his discovery, Juergenson went on to record hundreds of 'spirit voices' for the following four years and consequently published a book in Swedish in 1964 called "Voices From The Universe", this book was followed by another called "Radio Contact With The Dead"
Juergensons' book "Radio Contact With The Dead" was later translated into German and this caught the attention of Dr Konstantin Raudive a Latvian Psychologist. Dr Raudive was at first sceptical of Juergensons' claims but after many successful experiments, he too recorded hundreds of voices including that of his own deceased Mother. It is from Dr Konstantin Raudive that we get the term Raudive Voices.
Since the late 50's, many people have recorded voices on audiotape and now digital media and the obtaining of EVP samples has become common practice in the activities of those investigating paranormal activity.
The following experiment is to try and obtain voices etc onto Audiotape or Digital media. Please read the "What is Evp?" article for an explanation.
The first thing that we need is some form of recording device and the most popular is the small dictation machine that uses micro-cassettes. With the cost of digital devices coming down, the digital recorder is fast becoming popular.
Whichever form we decide to use, it is important that the device has a microphone socket and a headphone socket, most do! The use of headphones is important when listening back to recorded material in a noisy environment but in my opinion, headphones should always be used when reviewing material.The use of an external microphone is recommended because all mechanical recording devices are noisy due to the motor etc. The built in microphone on such devices are sensitive and will easily pick up mechanical sounds. A small tie clip microphone is ideal and the longer the lead between device and microphone the better.Digital devices won't suffer the same problems associated with motors etc but will always benefit from the flexibility of an external microphone. The plus side of digital is that apart from the initial outlay for the device and some rechargeable batteries, there is no tape to keep buying!
Now that we have decided on the recording device we are going to use it is time to try and obtain some evp samples. One of the most common ways of obtaining samples is with the use of "white noise" or "hiss" and this is provided by an untuned radio!Whether you have an analogue tuner (usually with a dial) or a digital scanning tuner, you need to find an area of hiss with no other signal (music/speech) present. A good starting point is 1475 kHz Medium wave, this will produce nothing but hiss (white noise) and this is exactly what we need.
With the white noise coming through the speaker/s, place the recording device nearby and record about 2 minutes of it. We record only short lengths because we will be listening over and over again to the same recording and believe me, not only is the level of concentration tiring on the ears but the hiss will get on your nerves!
Once you have roughly 2 minutes of audio it is time to listen back to it. What we are looking for is any form of voice or similar utterances and this may be as clear as day or way back in the hiss and barely audible. If you find that there is nothing to suggest voices on the recording, try another 2 minutes and then play that back but always remember to take a break from listening as it is tiring.
If you have access to some audio editing software such as Cool edit or Sound forge, we can analyse the sample of audio further but the way to do this is described in the "How to analyse evp with software" article so I won't go into any detail here.
The beauty of experimenting with evp is that we can try numerous approaches and methods. If you didn't manage to obtain any voice like anomalies with the above approach, try altering the distance between recording device and the radio speaker/s or taking a lead out of the headphone/line out socket of the radio and into the microphone socket of the recording device. Perhaps try another frequency where there is hiss or white noise. Try recording in a quiet room with no hiss only an external microphone. Whatever you try, remember to write down your method so then you can try and replicate the anomaly. This is especially so if you intend sharing the samples with other people or organisations.