EVP (Electronic Voice Phenomenon)
Voices of the dead are captured in an audio recording. In layman's terms, Electronic voice phenomenon is supposed to be exactly that; recorded voices from the afterlife. According to Wikipedia, electronic voice phenomenon or, shortly, EVP are sounds found on electronic recordings that are interpreted as spirit voices and might be intentionally or unintentionally recorded.
DEFINITION & CLASSIFICATION
As mentioned, Electronic Voice Phenomenon (EVP) is a sound or a voice which appears on a recording but has no known or scientific explanations for being recorded. Therefore, the sound or a voice is not heard during the recording session. Instead, it is heard later upon the reviewing of the tape. Mostly, such mysterious sounds are attributed to the spirit world since no known explanations could seemingly be found.
EVP varies from one to another; it could be an unfamiliar sound or an actual voice of a known or unknown person. The voice can vary in gender, tone, emotion or age; the voice can be easily heard or hard to even distinguish therefore requiring amplification and noise clearing to be heard; it can be a full sentence, phrase, one word or a simple sigh. An example of an EVP can be heard in a video bellow.
The following classification list is taken from
Long Island Paranormal Investigators
Class A - This type of EVP is loud, clear and of very high quality. The voice is easily understandable and does not need enhancement or amplification. Class A EVPs are also often (but not always) in direct response to a question being asked.
Class B - This is the most common type of EVP. This type of EVP is of somewhat lower quality and clarity than a Class A EVP but still very audible. Class B EVPs often do need some amount of enhancement or amplification to be heard clearer. The voice may not be clear enough to be totally understood or there may be disagreement as to what it is saying. Class B EVPs are often not in direct response to a question.
Class C - This is the lowest quality EVP. With a Class C EVP even the best enhancement and amplification may not be sufficient to make the voice audible or clear. There may even be debate whether or not an EVP is actually present.
Some paranormal investigators go further:
Class D - Occasionally referred to as Class R. There are very poor quality EVPs. Extremely questionable if it even is an EVP. Also referred to as EVP chatter, whispers, breathing noises and airy sounds. Some investigators use Class D as a "holding" classification until further analysis is performed. Either way, Class D EVPs are not used presentable as evidence.
Class G - Also known as the "garbage" because EVPs of such low quality that need extreme enhancement, filtering, etc. are probably not real EVPs. Even if later validated, with such extreme enhancement the reliability of the EVP is highly questionable. In other words, if you have to try that hard to make a sound an EVP then it probably isn't so.