SGHA Research

Expanding knowledge through disseminating information.

Disclaimer: The views and opinions expressed in this page are strictly those of the page authors. The contents of this page have been reviewed or approved by the Southwest Ghost Hunter's Association. All effort has been taken to maintain correct information at the time it was written. Some material may be dated and is archived within this section of our website. This article is copyright, 2002 by Cody Polston, Bob Carter and SGHA. All rights reserved.

 Articles ~ Research ~ Infrasound and paranormal experience

A multiphase study was performed to find an effective method to evaluate the effects of Infrasound as a possible cause for perceived paranormal events. The first phase developed criteria for controlled testing using an neutral environment (not known to be "haunted"). Monitoring devices were used in an effort to ensure that any extraneous low frequency sound would not interfere with the tests. A second phase involved a single-blind challenge of 10 people who were told the location was haunted, plus 10 people who were told that the building was not haunted (blank challenges).

We concluded that this study gives strong evidence that Infrasound may be responsible for some reported paranormal experiences.

Infrasound is sound with a frequency too low to be heard by the human ear. The study of such sound waves is sometimes referred to as infrasonics, covering sounds beneath the lowest limits of human hearing (20 hertz) down to 0.001 hertz.

It has been suggested that low frequency Infrasound may induce neurological effects that could explain many of the "experiences" that people have witnessed in haunted locations, particularly the feeling of being watched (sensed presence).

This article presents the preliminary data on infrasound tests under environmentally controlled and monitored conditions, using two known sound samples (19Hz and a 3 and 9Hz mix) played discreetly over a high quality sound system placed in an adjoined room.

Materials and Methods
This study was carried out in two phases.

1. The tests were carried out in an environmentally controlled area. The building was also selected because of it's ambiance (old and creepy). The major emphasis of this study was the evaluation of the effects of the sound waves. A 732A sound level meter was used to ensure the proper audio levels at the test site.

The test subjects were tested while they were sitting comfortably upright in a chair in the center of the darkened room with the speakers oriented towards them from an adjoining room. The exposure period lasted approximately 45 minutes per challenge.

2. This was a single-blind screening of 20 volunteers. The volunteers were told that they were participating in a concentration / mediation study and were to focus on a poster on the facing wall. During the interview process, 10 of the volunteers were given a reference that the location was "supposedly" haunted, the remaining 10 were not.

Sound Files

19Hz "ghost" tone

3 plus 9Hz "Sensed Presence" tone


Of the total of 20 people tested in the single-blind study, 17 reacted positively to the 19Hz tone while 13 reacted to the 3 and 9hz tone. The principal signs and symptoms produced were fear, nervousness, feelings of sadness and revulsion. All reactions were neurological.

Data Comparisons

The volunteer's perception (cause) of the phenomena varied. With the exception of 2 volunteers, only the subjects who had been told that the test site was haunted related the phenomena with ghosts. This indicates that the addition of information (such as a ghost story) is required for a person to connect the perceived effect with paranormal phenomena.

Back to SGHA articles