Any auditory response related to brain signals refers to binaural beat which originates from the nucleus of each cerebral hemisphere. A binaural beat is produced when two different auditory impulses of different frequencies crossover, run parallel or interact. Theoretically, binaural beat can be used to influence specific neural rhythms and can possibly be utilized to manage consciousness, or to entrain (draw along) the brain to a specific response.
Binaural beat was discovered by Heinrich Wilhelm Dove, a German scientist in 1839. The human reaction to binaural beat is an adaptation, a proof of evolution; the structure of the human brain has developed so that it can process two tonal elements so they sound like one. Classical example is the effect of a stereophonic headset where both channels feed different frequencies to the left and right ear. The resulting harmony is comparative to a binaural beat. The measurement of the cranium dictates what binaural beat a man can detect. Carrier waves below 1000 Hz are most effective because at this frequency the signal wave length is proportionately longer than the entire diameter of a grown man’s skull.
Sound frequencies below 1000Hz are diffracted by the skull, which can also be observed in radio wave projection. The distance that the sound needs to cover as it traverses across the skull produces different incoming signals; each ear gets only a fraction of the soundwave. Despite this disparity, the brain “hears” the input as another frequency, one that is an integration of both. Binaural beats can also be described as fluctuating rhythms composed of the resulting difference between auditory inputs of two different frequencies. Tones of higher frequencies are less detectable. At 8000 Hz it is the external ear that is activated.
Unofficial findings point to the ability of a binaural beat to facilitate the redirecting of brain waves and effect an altered state of consciousness. Depending on the end frequency of the beat, listening to binaural beat can either be relaxing or stimulating. Binaural beats between 1 and 4 Hz , as well as from 4 to 8 Hz can induce relaxation and can condition the listener into a meditative state. This type of binaural beat can be relied on to encourage restful asleep. Beats with a higher range of between 8 and 12 Hz can increase brain waves of the Alpha category. Those in the range of 12 to 16 Hz, on the other hand, are associated with increased alertness and enhanced memory.
Simply hearing binaural beats per se may not necessarily propel human beings into altered states of consciousness; there are several factors that influence stimulation like the openness and capacity of the listener to let go, calm down and concentrate. All these contribute to the effectiveness of inducing changes of a person’s state of mind.