Ghost Voices, EVP, and Science
Many ghost hunters, including the "Ghost Adventures" team, use voice recorders in an attempt to capture a supposed ghost voice, or Electronic Voice Phenomena (EVP). Often an investigator will hold the recorder while standing in the middle of a room addressing the supposed spirit, or while walking around. He or she will later go back and review the recordings at high volume, enhancing the audio and listening for any faint murmurs, sounds, or noises which could be interpreted as ghost voices. For example, a ghost hunter may ask out loud, "If there's a spirit here, what's your name?"
Often ghost hunters will get no answer at all; other times, if they wait long enough they'll hear some random sound that could be interpreted as a faint, mumbled name, such as "Mary." (Or maybe Terry, Kerry, Larry or Barry - never mind the fact that, as disembodied spirits, ghosts presumably do not have vocal cords, a tongue or a mouth that would allow them to speak.) One problem with EVP is that microphones are very sensitive and may record anything from someone talking in the next room, to wind blowing, to ordinary random sounds from outside, or even sounds from the ghost hunters themselves.