Essays, articles and resources with topics pertaining to application of technology and equipment used in paranormal investigating. For a descriptive list of these resources, see below.

  • Equipment List

    about ppi equipment list iconPPI uses an extensive array of environmental monitoring equipment during our investigations with hopes of capturing physical evidence of paranormal activity....

  • EVP: Acoustic Energy or Psychic Imprinting?

    The subject of Electronic Voice Phenomena or EVP has provided some of the most compelling evidence of paranormal activity ever captured. But the most intriguing characteristic of Electronic Voice Phenomena is that anyone with a quality recorder can capture it; the phenomena is available to any one willing to spend the time to investigate and carefully analyze their recordings.Read More

  • EVP: Infrasound, Ultrasound or Something Else?

    Over the years there has been a lot of debate regarding the nature of Electronic Voice Phenomena or EVP. One prevailing idea is that EVP is composed of either ultrasonic or infrasonic sound waves, and that is the reason why investigators are unable to hear EVP at the time of capture. Although this is an elegant idea, it is unlikely because it defies the basic understandings of acoustic energy.

  • Frank's Spirit Box

    Guest writer Dan Scott, an amateur ham radio operator and founder of, offers an informed and practical review of the controversial Frank's Spirit Box. 

  • Geiger Counters in Paranormal Investigations

    The idea of documenting environmental fluctuations at alleged haunted locations dates back to at least the 1930's, when serious paranormal investigators like Harry Price began applying the principals of scientific method to spontaneous paranormal investigations in the field. Price standardized the practice of environmental monitoring during his famous investigation of Borley Rectory, and his methodologies proved so compelling they are still used in the field today.

  • PPI Podcast #3: Tools of the Trade (2009)

    podcast trade tools iconPart 2 of PPI's presentation: Science and Beyond- An Educated Look at Ghost Hunting, is entitled Tools of the Trade. Presented by PPI Tech Manager and Co-Director Brian Miller.

    Recorded March 21, 2009 at Grossmont College, El Cajon, CA

    Length: 00:14:23


  • PPI Podcast #9: Tools of the Trade (2011)

    podcast trade tools iconPart 2 of our presentation: Science & Beyond - A Look at the Science Behind 21st Century Paranomrmal Investigation -is entitled Tools of the Trade. Presented by PPI Tech Manager Brian Miller.

    Recorded October 11, 2011

    Length: 00:19:25