Sound below the range of human hearing raises stress hormones and worsens mood — without anyone noticing it’s there.
STUDY: Scatterty KR et al, Front Behav Neurosci 2026;20:1729876
STUDY TYPE: Randomized controlled experiment
FUNDING: Natural Sciences and Engineering Research Council of Canada (NSERC)
Background
You can’t hear infrasound — sound waves below 20 Hz — but animals detect it and find it aversive. Fish flee from it. Some researchers have linked it to anxiety near wind turbines and creepy feelings in supposedly haunted spaces. Whether it affects humans in measurable ways has been unclear, and this study applied more rigor, testing the idea with a controlled design.
The Study
36 healthy undergraduate students randomly assigned to one of these four conditions:
1-2) Calming music with infrasound on or off
3-4) Unsettling music with infrasound on or off.
- Infrasound was delivered at ~18 Hz and 75–78 dB through concealed subwoofers. Participants couldn’t see the speakers or hear the infrasound above background noise.
- Self-report mood measures were collected immediately after a 5-minute audio clip. Salivary cortisol was collected at baseline and 20 minutes after the clip began.
- To check the blind, participants were then asked whether they thought infrasound was present.
Results
The blind was intact. They couldn’t tell if infrasound was present.
Despite that, infrasound shifted both mood and physiology. Compared to the infrasound-off groups:
- Irritability was higher (moderate effect size, η² = 0.10).
- Interest in the music was lower (η² = 0.12).
- The music was rated as sadder (large effect size, η² = 0.25).
- Salivary cortisol rose after exposure (rank-biserial r = 0.39).
These effects held across both music conditions, the calming and unsettling music, and weren’t explained by whether participants believed the infrasound was on. Infrasound raised cortisol even after accounting for self-reported irritability and fear, suggesting a physiological effect that goes beyond subjective mood. In a machine-learning analysis, sadness ratings, post-exposure cortisol, irritability during the clip, and disinterest were the strongest predictors of whether infrasound had been on.
Notably, infrasound didn’t raise anxiety. The effect was specific to irritability and disinterest, a pattern the authors interpret as annoyance rather than fear.
Limitations
- Small sample drawn from a single university, predominantly young women (75%).
- Only one infrasound frequency was tested (~18 Hz). Other frequencies may behave differently.
- Mood was measured only after exposure, not before, so within-subject mood change couldn’t be directly verified.
- Menstrual cycle phase and hormonal contraceptive use, both of which affect cortisol, were not recorded.
What About Those Old Houses?
Old houses often contain infrasound, from aging infrastructure like boilers, piping, and ventilation systems, particularly in basements.
I once stayed on the Queen Mary, a ship that is docked as a historic hotel off California. It is widely rumored to be haunted, and I heard a lot of ghosts. But as this American Hysteria podcast uncovers, the reason has more to do with something the Disney company installed and neglected to take out when they sold the ship.
Practice Implications
- Psychiatrists don’t often think about the acoustic environment when a patient seems inexplicably irritable or reports that their office, home, or workplace just feels off. This study gives those complaints a bit more biological traction.
- And yes, there’s more out there than our eyes can see.
— Chris Aiken, MD
Director, Psych Partners
Editor in Chief, Carlat Psychiatry Report
