Gary Galka was devastated by his 17-year-old daughter's death in 2004. The grief-stricken electrical engineer invented a machine that he claims can talk to the dead — specifically, daughter Melissa. Days after Melissa's death in a car accident, Galka said his daughter started communicating with him. "She started doing things like ringing the doorbell, changing TV channels, turning lights on and off," Gary Galka told a reporter from the Hartford Courant. "Then one time she came into my room and I felt her sit on the edge of the bed."
Galka built a hand-held device that he says can detect unusual vibrations or temperature variations in a room — all tell-tale signs, he says, of a spirit. He also built a voice recorder, a "spirit box" that can record the voice of the dead [source: Podsada]. Galka isn't alone in trying to find instruments that can communicate with the deceased. The idea intrigued Thomas Edison so much that after World War I, he decided to invent a spirit phone to dial up the dead. As far as anyone knows, Edison never built the machine or made a call, so it could have been a prank, too.
Ghost hunters also use a variety of mechanisms to talk to spirits. In their world, ghosts can appear as disembodied sounds on tape or digital recorders, or electric voice phenomena (EVPs). Skeptics say EVPs can be explained rationally, as radio interference or a person's mind playing tricks.