Introduction
Have you ever walked into an old building and felt an eerie presence, only to later learn it’s rumored to be haunted? While the spooky feeling might seem supernatural, science suggests a different culprit: infrasound. These low-frequency sound waves – produced by vibrating pipes, traffic, wind turbines, or even climate control systems – can trigger sensations of dread, unease, or the feeling of being watched. A 2023 study in Frontiers in Behavioral Neuroscience confirmed that infrasound is a key environmental factor in many alleged hauntings. This guide will walk you through how to investigate a supposedly haunted location for infrasound and other environmental triggers, just like psychologist Richard Wiseman did at Hampton Court Palace and the South Bridge Vaults in the early 2000s. By the end, you’ll be able to separate science from superstition.
What You Need
- Infrasound meter (or smartphone app capable of measuring low frequencies below 20 Hz)
- Magnetometer (to measure magnetic field variations)
- Hygrometer (for humidity levels)
- Light meter (to check lighting conditions)
- Notebook and pen (to record observations)
- Map of the location (with known ‘hotspots’ of reported phenomena)
- Willing participants (to report their feelings at each spot)
Step 1: Understand the Science Behind Infrasound and Ghostly Sensations
Before you start measuring, it’s important to know what you’re looking for. Infrasound refers to sound waves below 20 Hz – below the normal hearing range. These waves can be generated by natural sources (wind, earthquakes) or man-made ones (ventilation systems, heavy traffic, wind turbines, water pipes). Despite being inaudible, infrasound can make you feel physically uncomfortable, similar to the pressure change before a storm. Researchers have shown that such sensations are often interpreted as a “presence” or “ghostly” activity. In Wiseman’s studies, participants reported more odd experiences in locations that had variations in magnetic fields, humidity, and lighting – not just infrasound. So remember: infrasound is one piece of the puzzle.
Step 2: Identify Potential Sources of Infrasound at the Location
Walk around the site and note any mechanical or environmental noise sources. Look for:
- HVAC equipment (heating, ventilation, air conditioning) – often hums at low frequencies
- Plumbing – pipes can vibrate and generate infrasound
- Nearby roads or highways – traffic rumbles create low-frequency waves
- Wind turbines or large fans – known infrasound producers
- Elevators or escalators – motors sometimes emit infrasound
Make a list of these potential sources on your map. In Wiseman’s study at Hampton Court Palace and the South Bridge Vaults, he found that areas with rumored ghost activity also had measurable environmental differences, including magnetic field changes. Infrasound from nearby traffic might have contributed to those feelings.
Step 3: Measure Infrasound Levels at Key Locations
Use your infrasound meter or app to take readings in the areas where people have reported ghostly encounters. Follow these steps:
- Calibrate the meter in a quiet, neutral space.
- Take baseline readings in a part of the building with no reported activity.
- Record infrasound levels (in dB and frequency) at each hotspot for at least 2 minutes.
- Note any fluctuations – infrasound from intermittent sources (e.g., passing traffic) may be harder to catch.
Compare the hotspot readings to the baseline. If the infrasound is significantly higher (above 80 dB) and below 20 Hz, it could be influencing human perception. The study suggests that such frequencies can affect the brain’s angular gyrus, mimicking the sensation of a presence behind you.
Step 4: Check Other Environmental Factors – Magnetic Fields, Humidity, and Lighting
Use your magnetometer, hygrometer, and light meter to measure these variables at the same locations. Wiseman found that “haunted” spots often had stronger local magnetic fields, higher humidity, and dimmer lighting. Record:
- Magnetic field strength (in milligauss) – variations above 10 milligauss may be notable.
- Relative humidity (%) – sudden changes can cause feelings of stickiness or pressure.
- Lighting levels (lux) – low light (<50 lux) may increase suggestibility.
If a hotspot shows elevated infrasound plus one or more of these anomalies, it strengthens the case for an environmental explanation rather than a paranormal one.
Step 5: Conduct a Blind Participant Study (Optional but Powerful)
To replicate the core of Wiseman’s research, gather a small group of volunteers – ideally some who know the location’s ghostly reputation and some who don’t. Ask them to walk through predetermined spots (including both “rumored haunted” and control areas) and rate their level of unease or sense of presence. Do not tell them which spots are which. Later, compare their reports with your infrasound and environmental data. If participants report stronger sensations in areas with high infrasound (regardless of rumor knowledge), you’ve found a plausible cause. In Wiseman’s original studies, subjects reported more odd experiences in rumored haunted places even when unaware of the rumors, suggesting environment – not suggestion – drove the effect.
Step 6: Analyze and Interpret Your Findings
Compile all data in a table. Look for correlations between infrasound levels and the intensity of reported sensations. If the same hotspots consistently show high infrasound, abnormal magnetic fields, and high humidity, you can confidently attribute the “haunting” to environmental factors. Remember: one factor alone may not be enough – the combination likely works together. For example, infrasound might cause a subtle pressure feeling, while a strong magnetic field could directly stimulate the brain’s temporal lobe, leading to a stronger “presence” sensation. Write up your conclusions, noting that the location’s mechanical systems or nearby infrastructure are the most probable culprits.
Tips for Successful Infrasound Investigation
- Be thorough: Take measurements at different times of day – infrasound from traffic or machinery may vary.
- Stay objective: Avoid confirmation bias. Measure control spots even if they seem “normal.”
- Cross-check with other studies: Compare your findings to known research on infrasound and perception, such as the 2003 Wiseman studies or the newer 2023 paper.
- Use multiple meters if possible – cheap apps can be unreliable; a professional infrasound microphone gives more accurate data.
- Consider psychological factors: Even if infrasound is absent, strong beliefs or stories can shape experience. Keep participants blind to study goals.
- Document everything: Photos, audio recordings, and timestamped notes help later analysis.
By following these steps, you’ll not only demystify supposed hauntings but also contribute to the scientific understanding of how our environment shapes perception. The next time someone says a house is haunted, you can reply: “Let’s check for infrasound first.”