Researchers from the Norwegian University of Science and Technology (NTNU) and University College London have uncovered a possible explanation for why some people are especially sensitive to low-frequency noise. Their findings were published in the journal Scientific Reports.

The study focused on infrasound—sound waves with frequencies below 16 Hz. Such low-frequency sounds can be generated by ventilation systems, heat pumps, wind turbines, electrical transformers, industrial machinery, and transportation.

Although infrasound is commonly considered inaudible, the researchers note that humans can perceive it when it reaches sufficiently high intensity.

The team found that the inner ear processes infrasound differently from ordinary sounds. While normal hearing primarily relies on specialized sensory hair cells, extremely low-frequency sounds appear to activate a different population of cells within the inner ear that normally regulate the sensitivity of the auditory system.

According to the researchers, this mechanism may explain why low-frequency noise is often experienced as a deep hum or even as a physical vibration rather than a conventional sound. Differences in how this system functions from person to person may also explain why some individuals barely notice infrasound, whereas others experience significant discomfort.

The researchers hope that these findings will improve understanding of low-frequency noise sensitivity and contribute to the development of strategies to reduce its impact on people's health and well-being.