Influence of Binaural Beats on EEG Signal

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.