Why did this happen?

In 2006 during deer season my cousin killed a huge buck, he brought it home and his wife grabbed the camcorder and began to film him beside the buck. He and his wife were the only ones at home, everyone calls his wife Tina, short for Katina, but as she filmed and all was silent between the 2 of them a mans voice called out her name, Katina. Neither of them heard the voice until watching the video later. I myself have watched and heard the video also, and it is a mans voice and I must add it sounds very spooky. There is a graveyard about 500 feet from there house, could this have anything to do with it?