Influence of Infrasound on the Alpha Rhythm of EEG Signal

Abstract

The alpha waves were rst registered and named by Berger in 1929. They are oscillations in the frequency range 812 Hz, originating from the occipital lobe during wakeful relaxation with closed eyes. The alpha blockage is the result of desynchronisation of the bioelectric activity of the brain induced by sensory stimulation. When the subject's eyes are closed, the alpha rhythm is generated. As soon as the eyes are open, alpha disappears. This is called alpha block and may be elicited also by any form of sensory stimulation. This replacement of the alpha rhythm is also called desynchronization because it represents a change of the synchronized activity of neural elements. This state is also called arousal or alerting response. Infrasounds are acoustic waves of frequency below 20 Hz. They are not directly perceived by humans because the natural frequency of vibrations of the part of the basilar membrane distant from the round window is about 20 Hz. The hearing organ, therefore, is well adapted to receive waves with frequency in excess of 20 Hz. The purpose of the experiment was to determine the eects of infrasound waves on variations in the alpha waves. Tests were done on a group of 32 participants. The experiment showed that infrasounds of frequency f = 7 Hz and acoustic pressure level SPL = 120 dB (HP) cause a statistically signicant reduction of the alpha rhythm power.

Archives of Acoustics

“…We expected that studying a relationship between the perception of and the brain's response to IS and LF sounds might allow in the future a better understanding of individual complaint cases attributed to these sounds. Kasprzak (2012) examined the effect of airborne IS stimulation (7 Hz at 120 dB SPL; well above threshold according to (Møller, Pedersen, 2004)) on electroencephalography (EEG) patterns and found a significant reduction in the alpha (8-12 Hz) rhythm power when subjects were stimulated by IS. A similar result was found by Kasprzak (2013) using very narrowband (4-8 Hz) IS noise.…”

The Effect of the Narrow-Band Noise in the Range 4-8 Hz on the Alpha Waves in the EEG Signal

“…Tests were carried out on a group of 32 participants. The experiment showed that infrasounds of frequency f = 7 Hz and acoustic pressure level = 120 dB (HP) cause a statistically signicant reduction of the alpha rhythm power [7].…”

Archives of Acoustics

“…That is undesirable and should be estimated. The authors undertook the research to diagnose the plausible side effect of structure-born noise of such barriers because it may influence human body (Kasprzak, 2014). As a mechanical structure, the acoustic barrier is characterized by mechanical parameters which, in the field of modal analysis, are made up of natural frequencies, damping factors and mode shapes.…”