Binaural beats are subjective hearing sensations, which occur when one of tone signals is applied to one ear, and the other one, with a slightly different frequency is applied to the second ear. A listener then receives a resultant sound with an amplitude which changes with a frequency equal to the difference of frequency of applied signals. The aim of this thesis was to examine the influence of binaural beats on changes in the morphology of the brain bioelectrical signal. Verification of previous studies, such as stimulation of binaural beats affects the brain and can cause changes in other frequency bands. Previous studies have been conducted on individual leads and dealt with the occurrence of follow up effect. In the research there were used binaural beats with a frequency of f = 10 Hz. The left ear was exposed to a signal with a frequency of 100 Hz, and the right ear -to a signal with a frequency of 110 Hz, the acoustic pressure level SPL = 73 dB. The research was conducted on a sample group of 20 people. The analysis of average amplitudes of spectral density function of EEG strength signal proved that the exposition of binaural beats brought about a follow-up effect, which means that a component frequency in the EEG signal morphology was observed which corresponds with a frequency of the exposed binaural beats. It was also noted that during the exposition of binaural beats, there occurs a statistically significant decrease of average amplitudes of spectral density function of EEG strength signal for alpha and beta frequency ranges. However, it was observed that the amplitude of spectral density function of the strength has increased in theta frequency range.
This study investigates how infrasound exposure should influence the electrocardiograph (ECG) patterns and the functioning of the cardiovascular system. Infrasound waves are widespread and common and now perceptible in the working environment (particularly in industry) as well as in the recreation grounds (natural sources of infrasounds). the main sources of infrasounds include heavy machines, transport and materials handling installations, as well as natural phenomena, such as blowing winds, storms or flowing waters. Research work has now established that low-frequency noise affects the morphology of the electric biopotentials of human brain and influence the blood pressure, the level of electrodermal activity and visual-motional coordination in humans. the effects of infrasounds on fluctuations of the ECG patterns have received little attention so far. This study summarises the research data to determine how low-frequency noise with frequency f = 7 Hz and the acoustic pressure level SP L = 120 dB (HP) should influence the ECG patterns. Experiments were performed on a group of 33 participants. Thus obtained experimental data indicate that infrasound exposure leads to major changes in the functioning of human heart.
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.
The purpose of this paper is to determine the eect of infrasound noise from wind turbines (up to 20 Hz) on the changes in the EEG signal patterns in humans. The experimental study was undertaken to investigate the eect of a 20 minutes long infrasound exposure on humans. The acoustic signal was recorded at a distance of 750 meters from the wind turbine and the frequency components above 20 Hz were then ltered out. Research work undertaken so far to investigate the impacts of wind turbine noise on humans would mostly rely on questionnaire tools and subjective assessment given by respondents. This study focuses on the eects of infrasound noise from wind turbines on variations of EEG signal patterns in an attempt to develop a more objective measure of the infrasound noise impacts. The experimenal study was conducted in a pressure cabin where the EEG procedure was performed. Analysis of the EEG signals reveals the changes between the EEG patterns registered during the three successive stages of the study.The results indicate some changes in EEG signal patterns registered under exposure to wind turbine noise. Moreover, the specic frequency ranges of the EEG signals are found to be altered.
The problem of low-frequency acoustic waves emitted by wind turbine farms has become a great challenge to acousticians in Europe for more than 20 years. In Poland wind farm industry is growing rapidly and generates questions about the inuence of such sounds on human organism. A short survey of previously published reports concerning subjectively perceived inuence of wind turbines on people living next to wind farms is given together with the results of the Thayer's test measuring the dierence in activation level before and after exposition on infrasound wave generated by a wind turbine. Statistically signicant increase of the High Activation Level representing a tension type arousal has been revealed.
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