EVP is an acronym for Electronic Voice Phenomena. In simple terms it's a recorded voice that usually isn't able to be heard by the human ear. We use digital voice recorders during our investigations. When the recordings are later downloaded into a computer and lightly filtered, voices of those other than the investigators or residents can sometimes be heard. Most often these sounds are simple statements or single words. As with many aspects of paranormal investigations there are no set rules in this field, but our group does have a set of guidelines we find work well for us. Some of these are:
1. Limit the number of people on an investigation. By their very nature EVPs can be hard to make out and it only creates more confusion and work for the investigator when you have more than 3 or four people present.
2. Limit how much filtering you do to any recording. Filtering should only be used in an attempt to limit background noise making the possible EVP clearer and easier to make out. When you filter excessively, the sounds will seem altered and mechanical.
3. Have those investigators or residents present speak clearly and normally when talking. Some people automatically start speaking softly when they realize there is a recorder on in order to avoid having their voice on the recording. This only causes more confusion as the investigator tries to listen to the recordings later at their home.
4. Consider your surroundings. I've listened to possible EVPs that were taken in tunnels, caves, and other places where you are likely to get echo's and other odd variations of the human voice. Also consider that voices can sometimes carry longer distances over bodies of water.
5. Accept that sometimes you just won't know what is being said