EVP

EVP stands for Electronic Voice Phenomenon. It's supposedly recorded sounds or voices of paranormal nature on radio or tape recorders. Some people believe that these voices are caused by ghosts or spirits who are trying to communicate with humans. EVPs are usually short and it takes a little bit (sometimes a lot) of time to decipher the voice. What paranormal investigators would do is walk around the location with the recorder and just ask questions such as, "Is there any astral being that wishes to talk to us?" or a more direct question like "Why are you still here"?, etc. Then they would wait for around 15-20 seconds before asking another question.

There are three types of EVP recordings*:
-Class A: To be considered as Class A, the EVP recordings must be able to be heard and understood clearly with a speaker by most people.

-Class B: Class B recordings include recordings that can be heard over a speaker but are a little bit hard to understand. Most EVPs fall under this category.

-Class C: Class C recordings can only be heard with a pair of headphones and are hard to understand. Keep in mind that not all EVPs can be understood.

*Source: http://ghosthuntingsecrets.com/blog

Believers in the paranormal have several explanations for EVP*:
- Discarnate entities: ghosts or spirits are not able to talk directly with humans but somehow they're able to "imprint" information on recording media.

-Psychokinesis: By definition, psychokinesis means "the ability of the mind to influence matter, time, space or energy by means outside the laws of physics". On EVP, communication might be done by humans through an "unknown form of matter/energy manipulation".

-Extraterrestrial entities: Sarah Estep, the founder of the American Association of Electronic Voice Phenomena (AA-EVP) believes that EVP might be caused by extraterrestrial beings.

Skeptics of the paranormal also have several explanations*:
- Interference: The frequency of the EVP recording devices can mix with the frequency of other electronic devices (intermodulation) which forms additional signals. These interference can be recorded as phenomena.

-Auditory pareidolia: By definition, auditory paredolia means a condition where the brain "incorrectly interprets random patterns as familiar patterns". In EVP's case, it's when the investigator interprets random sounds as human voice.

-Apophenia: It's human's tendency to "spontaneously find meanings or connections" in random things.

-Capture errors: These are noises that result from "over-amplification of a signal at a point of recording".

-Processing artifacts: These result from attempts to increase the quality of an existing recording through re-sampling, frequency isolation, noise reduction or enhancement which can alter the way the existing recording sounds.

-Hoaxes: Some recordings are simply regarded as frauds.

*Source: Wikipedia