How an EVP is actually captured in a recording is still not understood by parapsychologists. Of course, what we do know is that ghosts and spirits don't have physical bodies. Therefore, they have no vocal cords, so it could be argued that they can't produce a voice in the same way that living humans do.

However, this isn't strictly true. It's widely agreed upon by paranormal investigators that ghosts are sometimes able to move objects, slam doors, and break items. Therefore, they must at times be able to take a physical or partially physical form, or at the very least be able to manipulate the physical world around them. If this is the case, then they may also have the ability to vibrate the air around them in order to make sounds, which are at a basic level vibrations in the air.

The idea that they can do this either at will...