Lesson: Infrasound is perhaps the most important element of the proposed concept

Testing the body’s stress response

A casual conversation with neuroscientist (and co-author) Kale Scatterty inspired the latest research. Scatterty co-author 2023 paper showing zebrafish’s aversion to infrasound, a particular concern that caused the fish to avoid certain areas. This showed a physiological response to infrasound, and Schmaltz wanted to see if this was true in humans. So they created a lab-based experiment to test the idea that cortisol levels in people’s saliva — part of the body’s response to stress — might increase in response to infrasound.

A view of the test area and the equipment used to produce infrasound.

Credit: KR Scatterty et al., 2026

Thirty-six participants sat alone in a room and were played gentle music similar to what one would hear in a yoga class, or “very distracting music,” according to Schmaltz, half of whom were also exposed to infrasound produced from hidden subwoofers. “What we thought would happen is when infrasound started, people would find soothing music to be relaxing, while scary music would be scary,” he said.

In fact, the results showed that, across the group, the participants became more depressed and restless when the infrasound was turned on, regardless of the type of music playing, and their cortisol levels increased significantly. None of the participants could tell when the infrasound was present. This shows that people can have a physical response to infrasound even if we can’t consciously hear it.

Although these are encouraging results, infrasound may not be the only thing that causes us to think hard; it’s probably one of several, including Wiseman’s first discovery of the concept. “It’s not infrasound that ’causes’ the confusion,” Schmaltz said. “I want to be clear about this. We are not saying that we have solved the problem. But in some of these old buildings, there may be a few pipes (producing infrasound), and if someone already has the hope that something dangerous may happen, infrasound can drive it a little.