TRONDHEIM — Researchers at the Norwegian University of Science and Technology and University College London published findings in the journal Scientific Reports indicating that support cells in the inner ear generate electric fields that enable the perception of infrasound. This mechanism differs from the way normal sound is processed by the ear.

Carlos Jurado, a postdoctoral fellow in the Department of Neuromedicine and Movement Science at the Norwegian University of Science and Technology, and Torsten Marquardt, affiliated with University College London, co-authored the research. Infrasound is defined as sound below 16 Hz.

Humans can perceive infrasound if the sound level reaches a sufficient intensity. Jurado stated, "Humans can actually perceive infrasound if the sound level is high enough." Specialized sensory hair cells in the inner ear are typically responsible for transmitting sound signals to the brain. However, at very low frequencies, signals to these hair cells can become too weak. Jurado added, "But at very low frequencies, the signals to these hair cells become too weak, and other hair cells, which normally contribute to the hearing process, can still pick them up."

The research indicates that the support cells in the inner ear, which usually receive signals from the brain to adjust hearing sensitivity, are capable of generating electric fields. These electric fields are strong enough to trigger nerve signals that are then sent to the brain, leading to the perception of infrasound. Low-frequency sound is often experienced as a hum or a physical sensation rather than a distinct high-frequency sound.

Low-frequency noise can originate from various sources, including ventilation systems, heat pumps, wind turbines, industrial activity, transport, generators, and transformers. Small increases in sound pressure can lead to a perception of louder low-frequency sound. The mechanism for perceiving infrasound may also vary among individuals.