Overview of Science Friday: Is That Spooky Old House Full of Ghosts, or Just Infrasound?
This episode explores the idea that “haunted” feelings in old houses may be caused not by ghosts, but by infrasound—low-frequency sound waves below the range of human hearing that can still affect mood and physiology. Host Flora Lichtman first speaks with psychologist Dr. Rodney Schmaltz, whose research suggests infrasound can raise stress levels and make environments feel creepier or more unsettling. The second half shifts from spooky buildings to the natural world, where Dr. Milton Garces explains how infrasound is produced by volcanoes, earthquakes, storms, oceans, and even asteroid impacts, and how scientists use it for monitoring and early warning.
Haunted Houses and the Psychology of “Ghostly” Feelings
What infrasound is
- Infrasound is sound below 20 Hz, generally too low for humans to consciously hear.
- Even if we can’t hear it, we can often feel it as vibration, tension, or unease.
- Common sources include:
- Old boilers and pipes
- Heavy machinery
- Traffic
- Subways
What Rodney Schmaltz’s study found
- Participants were exposed to infrasound in the lab while listening to either:
- relaxing music, or
- creepy ambient horror-style sounds
- Across both conditions, infrasound was linked to:
- higher cortisol levels
- increased irritation
- music being rated as sadder and less interesting
Why this matters for “haunted” places
- Schmaltz argues that people may walk into a dark, old basement, feel something physically unsettling, and interpret it as paranormal.
- The experience is real, even if the explanation is environmental rather than supernatural.
- Expectation also matters: if a place is already believed to be haunted, people are more likely to interpret strange sensations as ghostly.
Ongoing research
- His team is now testing whether supposedly haunted locations in Alberta have higher infrasound levels than control buildings.
- Measuring infrasound requires specialized, expensive microphones.
Infrasound in Nature: Volcanoes, Earthquakes, and More
Where natural infrasound comes from
Dr. Milton Garces describes infrasound as a “zoo” of hidden sounds produced by large or powerful natural events, including:
- Volcanic eruptions
- Hurricanes
- Earthquakes
- Ocean waves
- Asteroid impacts
- Even biological rhythms like the heartbeat and breathing
Why scientists study it
- Infrasound can travel around the world multiple times if the source is large enough.
- It helps provide early warning for:
- volcanic eruptions, especially for aviation safety
- tsunami-generating eruptions, like the 2022 Tonga event
- Global infrasound arrays were originally developed for monitoring clandestine nuclear tests, but they now support broader scientific observation.
Sonifying the “unhearable”
- Garces works on making infrasound audible through sonification.
- This is technically difficult because shifting ultra-low frequencies into the audible range can distort the sound.
- One standout example is the Tonga eruption, which produced a rare acoustic phenomenon Garces calls a “sonic unicorn” because it hadn’t been seen in over a century.
Key Takeaways
- Not every spooky sensation means a ghost is present.
- Infrasound can trigger real physical and emotional responses without being consciously heard.
- Old buildings, basements, and industrial spaces may contain environmental conditions that feel eerie.
- Infrasound is also a major tool in geophysics and hazard monitoring, helping scientists track dangerous natural events.
- The episode highlights a broader theme of science communication: taking people’s experiences seriously while offering testable, evidence-based explanations.
Notable Insight
“People are experiencing something. It’s a genuine feeling.”
That idea connects both interviews: whether in a haunted house or near a volcano, the experience is real—the question is what’s causing it.