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Binaural beats are a tone created in the brain when it is presented with two different frequencies at the same time. When signals of two different frequencies (sounds) are presented, one to each ear, the brain detects phase differences between these signals. A perceptual integration of the two signals is perceived in the brain, producing the sensation of a third “beat”. The binaural beat is perceived as a fluctuating rhythm at the frequency of the difference between the two auditory inputs.
The binaural hearing beats occur in the brain stem in response to auditory stimulation produced by two pure tones of slightly similar frequency, each in a different ear. The upper grove located in the brainstem is responsible for interpreting the frequency difference, which is called the binaural tone. For example, if we issue a 110 Hz tone in the right ear and another 115 Hz tone in the left ear, the frequency difference between the two will be 5 Hz, and this is the binaural tone.
Binaural beats were discovered in 1839 by a German experimenter, H. W. Dove. Over the last several decades, the Monroe Institute () has researched and utilized binaural beat technology as a therapeutic tool for enhancing consciousness and treating various disorders. The human ability to “hear” binaural beats appears to be the result of evolutionary adaptation. Many evolved species can detect binaural beats because of their brain structure. The frequencies at which binaural beats can be detected change depending upon the size of the species’ cranium. In humans, binaural beats can be detected when carrier tones are below approximately 1500 Hz. It is this innate ability of the brain to detect phase differences between the ears that enables the perception of binaural beats.
Binaural beats can easily be heard at the low frequencies (< 30 Hz), that are characteristic of brain rhythms within the EEG spectrum. There is a vast and informative body of research on the effectiveness of binaural beat frequencies in creating desired patterns of brainwave activity. More and more research efforts are reporting changes in consciousness associated with binaural beats. The subjective effect of listening to binaural beats may be relaxing or stimulating, depending on the frequency of the binaural-beat stimulation. Binaural beats in the delta (1 to 4 Hz) and theta (4 to 8 Hz) ranges have been associated with reports of relaxed, meditative, and creative states, and used as an aid to fall asleep. Binaural beats in the alpha frequencies (8 to 12 Hz) have increased alpha brain waves and binaural beats in the beta frequencies (typically 16 to 24 Hz) have been associated with reports of increased concentration or alertness and improved memory. This research demonstrates the way binaural beat technology is effective in reducing symptoms of anxiety, insomnia, depression, and other disorders, while increasing levels of relaxation, creativity, and balance.
Most studies of binaural beats use a technique called "masking" to hide the presence of the beating from conscious awareness. Pink and white noise are the most common masking agents utilized to disguise binaural beats, so the listener is unaware of their presence. The terms "pink" and "white" noise refer to how energy is distributed acoustically: pink noise is equal portions of energy per octave, whereas white noise is equal energy per frequency. When perceived by a listener, pink and white noise resemble a static-like sound like a television channel without a signal.
Binaural beats can have an influence on the emotional states of a person. Nowadays devices for binaural beats are sold worldwide with advertised benefits like increased focus and concentration by listening to the respective binaural beats regularly. Identifying binaural beat samples or frequencies that demonstrably enhance these emotional states can support people to deal with daily activities and improve health care processes.
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