There's no agreed-upon mechanism that explains how voices are captured as EVPs. In fact, even the origins of these voices are disputed. One thing that most paranormal investigators agree upon is that most hauntings fall into one of two categories: residual hauntings or intelligent hauntings. These classifications may also be relevant to EVPs.

Residual hauntings are a type of haunting where the witness is seeing, sensing, or experiencing the residual psychic or emotional energy of a person or an event that took place at that location in the past. For this reason, residual hauntings are sometimes called place memories.

Residual hauntings are said to be an imprint of energy that has been left behind by someone who suffered a tragic, premature death, usually a murder, suicide, or execution. The belief is that the energy used by the body and the brain in resisting death can be so immense that those events can...