Infrasound and the Hidden World: How Low-Frequency Rumbles Shape Fear and Nature

Podcast at a Glance

In the podcast, host Flora Lichtman speaks with psychologist Dr. Rodney Schmaltz about how infrasound, a low-frequency rumble below human hearing, can affect mood and perception, potentially explaining hauntings in old houses. The discussion shifts to fieldwork in Alberta to compare supposedly haunted locations with control sites, and to the work of Dr. Milton Garces on infrasound in nature, including its role in volcanic eruptions and tsunami warnings. The episode highlights how expectation, environment, and inaudible vibrations can shape experiences and scientific understanding.

Key Insights

• Infrasound exposure can elevate cortisol and alter mood irrespective of music type.
• Lab and field work explore whether haunted locations have higher infrasound levels than non-haunted places.
• Infrasound is pervasive in nature and has practical applications in early warning systems for eruptions and tsunamis.
• The episode emphasizes evaluating experiences skeptically while respecting genuine perceptual effects.

Overview of the podcast

The podcast investigates infrasound, a low-frequency sound below 20 Hz that is not consciously heard but can be felt. The host, Flora Lichtman, guides a discussion with Dr. Rodney Schmaltz, a psychology professor at McEwen University, about his research on how infrasound influences people in controlled lab settings. Schmaltz describes a study where participants are exposed to infrasound or not, while listening to relaxing or ambient spooky sounds. Across both conditions, cortisol levels rise modestly during exposure, and participants report feeling sadder and more irritated. The important takeaway is that the physiological and perceptual effects of infrasound appear to occur even when people are not aware of the stimulus, suggesting a possible mechanism contributing to hauntings in certain settings.

Infrasound in the Lab: Mechanisms and Measurements

The core of Schmaltz’s discussion centers on how infrasound operates in the human body. Infrasound is described as a background rumble produced by boilers, heavy machinery, traffic, and other large-scale sources. In Schmaltz’s experiments, researchers expose participants to infrasound in a lab environment and measure responses such as cortisol, a stress hormone. The results show an uptick in cortisol in the presence of infrasound regardless of whether the accompanying sound is spooky or relaxing. Participants also report feeling sadder and less interested in the music. Schmaltz notes that this suggests a cognitive-emotional response to the physical sensation of infrasound, even when individuals are not consciously aware of the sound’s presence. The researchers also consider whether longer exposure might yield habituation or cumulative stress, acknowledging the need for further study to clarify longer-term effects and potential confounds related to urban noise and environmental factors.

Haunted Experiences and Cognitive Gaps

From Schmaltz’s perspective, people may interpret infrasound as evidence of paranormal activity because they enter environments with contextual cues that prime expectations. If a room is dark and described as haunted, the brain’s predictive processes may amplify perceptual and emotional responses when exposed to subtle physiological cues like infrasound. The host emphasizes taking experiences seriously while pursuing scientific explanations. Schmaltz argues that understanding how expectation drives anomalous experiences can help people become more discerning consumers of information, filling cognitive gaps with plausible, evidence-based interpretations rather than mysticism.

Field Work: Alberta Haunt Locations

The conversation moves to Schmaltz’s ongoing follow-up study, which involves measurement of infrasound at several locations in Alberta, including venues that are purported to be haunted and control buildings. The team aims to determine whether the supposedly haunted places actually exhibit higher infrasound levels. Schmaltz acknowledges the technical challenges of measuring infrasonic waves, noting that specialized microphones are expensive. He also offers a practical, non-technical sign of infrasonic presence: a candle flame bending and wavering in the middle when infrasound is present. While this observation is not a rigorous measurement, Schmaltz uses it to illustrate how infrasound can manifest in everyday environments and how observers might intuit a link to haunting phenomena.

Infrasound in Nature: Milton Garces’s World

The second segment shifts to Dr. Milton Garces, director of Hawaii’s Infrasound Laboratory, who describes infrasound as a pervasive aspect of nature, produced by oceans, weather systems, volcanic activity, and other large-scale natural processes. Garces likens infrasound to the heartbeat of the Earth and explains that the ear does not respond to these frequencies unless the sound is strong enough to be felt as vibration. He discusses how infrasonic waves can travel around the world and be used for monitoring and early warning purposes—such as monitoring volcanic eruptions to steer aircraft away from ash clouds and detecting tsunamis generated by oceanic eruptions. Garces also shares recordings from significant events, such as the 2022 Tonga eruption, which produced a unique infrasound signature that had not been heard in over a century, illustrating the scientific and emotional impact of capturing these sounds for the first time in modern instrumentation.

Sonification and the “Sonic Unicorn”

Garces discusses the artistic and technical challenges of turning infrasonic data into audible sound. He recounts the difficulty of translating extremely low frequencies into sounds without introducing artifacts, describing how certain signals, like a central frequency around 30 minutes per cycle, resist straightforward transcription. He calls some rare phenomena, such as the Lamb wave associated with Tonga’s eruption, a “sonic unicorn” because it defies easy transcription. The discussion highlights the balance between preserving the scientific integrity of infrasonic signals and creating engaging auditory representations that convey the power and scale of natural events.

Applications and Implications

Throughout the podcast, the speakers stress that infrasonic research sits at the intersection of physics, physiology, psychology, and public communication. For Schmaltz, the practical goal is to improve science literacy and help people reflect empirically on their personal experiences. For Garces, the goal is to expand the use of infrasound in monitoring natural hazards and protecting lives and property. The episode underscores the importance of rigorous measurement, replication, and cautious interpretation when linking experiences to physical phenomena. It also demonstrates how two domains—human perception and planetary-scale processes—can be informed by the same underlying physics of sound that operates beyond the range of human hearing.

Takeaways for Science Communication

Audience members are reminded that experience matters, but explanation matters even more. Infrasound offers a compelling example of how something invisible can shape what people believe and how scientists can approach such experiences with curiosity, skepticism, and methodological care. The podcast invites listeners to consider that hauntings might arise not from supernatural forces but from environmental physics interacting with cognitive expectations, while also recognizing the real, measurable effects in both lab and field settings. This dual focus on evidence and experience exemplifies the broader mission of presenting credible, accessible science that connects complex phenomena to everyday life.