The sound produces in man a profound effect. But while there is no scientifically valid explanations of the impact of a particular sound on different aspects of our psyche.
The result of the influence of sound develops, among other things, and from subjective experience. Rain sounds in the forest will be more relaxing than the sound of running factory on many people, partly because more pleasant associations occur in people due to the perception of nature, not of production processes, because man is part of nature.
But there is a backlash when it comes to person, having pleasant memories of a childhood spent at his father´s factory, but the painful memories of how he got lost in the woods.
Binaural beats are two tones with slightly different speed (or frequency) and supplied separately in each ear. These rhythms are perceived as if they occur in my head.
This effect is produced in the brain, not the ears, as in the case of monaural beats. It is a mixed product of the activity of neurons located in the region of the ear, and the brain. Binaural beats are different from monaural rhythms that occur in the environment (external to the ear), it´s like if you hit simultaneously by two guitar strings, having a slightly different frequency.
With monaural rhythms, the musicians tune stringed instruments. As monaural and binaural beats, is the result of the arithmetic sum of the two tones volgofarm, whereas they complement or "deny" each other, becoming louder, then quieter and louder again.
Binaural beats were first discovered in 1839 by German experimenter H. Dove). Then binaural beats were considered a kind of monaural rhythms. Monaural and binaural beats are rarely encountered in nature, but in the objects created by man, occur frequently.
For example, two large motor running at different speeds, and send large waves of vibration through the deck of the ship or jet engine aircraft. The lower of the two tones is called the carrier, and a higher tone is called the successor. Fig. 2 shows how the monaural and binaural beats with a frequency of 24 Hz are produced by the mixing of two tones with a frequency of 143 Hz and 167 Hz.
When a person hears fewer than three binaural beats a second, the rhythms seem to move back and forth inside the head. Motion perception is the result of the way the brain processes sounds. For low frequencies the brain determines the rhythm of the sounds, noting the difference in phase angle between the sounds.
The brain cannot well handle the relationship between the phases at high frequencies and, thus, determines the difference between the amplitude of sound entering the ear at the same time.
This explains why one of the differences between the perception of monaural and binaural beats is that monaural rhythms can be heard at any speed, whereas binaural beats are perceived better at a lower speed and is best observed at a frequency of 440 Hz. (Binaural beats with a carrier frequency of 900 Hz is usually not observed.)
When two tones, used to obtain binaural beats, are very different in frequency, they are perceived as 2 different tones due to the fact that the difference in the relationship of the phases between the two tones appears too quickly to the brain was able to define their relationship.
There is a test to measure the range of binaural beats that can be perceived at a different frequency carrier. He found that with a quick rhythm that can be heard up to the moment when the brain will perceive it as two different tones, has a frequency of 25 Hz with a carrier frequency of 440 Hz.
In other words, if two different tones have frequencies more than 25 Hz apart, you will hear two different sound, and not as a binaural beat. When the frequency carrier is above or below 440 Hz, the perception of separate tones appears at a lower frequency rhythm.