Effect of low-frequency sounds on cortisol levels and emotional state

Infrasonic vibrations are a constant element of the modern urban and industrial environment. They can be generated by both natural processes, such as stormy winds or seismic activity, and anthropogenic sources, such as ventilation systems, heavy industrial equipment, and transportation networks. Although the human ear cannot consciously identify sounds below 20 Hz, the body reacts strongly to these stimuli. Scientists have studied the impact of this inaudible factor on mental and physical well-being.

In a controlled experiment, a group of 36 volunteers was exposed to 18 Hz infrasound. The procedure was conducted in a way that prevented the participants from knowing when the equipment was turned on. The main biochemical marker of stress was the level of cortisol in the saliva, which was measured before and after the session. The results showed that exposure to infrasound resulted in a statistically significant increase in the concentration of this hormone. Additionally, the participants reported an increase in irritability and a decrease in cognitive interest, although they were unable to explain the cause of their changes.

An important aspect of the work was the explanation of subjective experiences that are often interpreted as paranormal. In old buildings or basements, worn-out pipes and ventilation systems generate low-frequency vibrations. When a person enters such a field, their body reacts by releasing cortisol, which causes a state of heightened alertness and anxiety. If there are cultural beliefs or prior knowledge about the building’s “haunted” nature, the brain may mistakenly attribute the physiological stress to external supernatural entities. Thus, infrasound can act as a physical trigger for the formation of mystical beliefs.

The authors of the study point out the need for further research on the long-term effects of infrasound on public health. The constant activation of stress mechanisms under the influence of man-made vibrations can have a cumulative effect, negatively affecting mental well-being and overall physiological status. The findings may contribute to the revision of standards for the permissible level of low-frequency noise in the design of residential and office spaces. Further research will focus on studying a wider range of frequencies and exposure durations to provide a comprehensive understanding of the body’s neurobiological response.