The average human being with no hearing loss is able to hear anything from 20 Hz and 20k Hz, yet all the binaural beat frequencies range below this audible minimum, so how is it even possible that as a human you are able to know that your binaural beat therapy is working effectively?
Here we will discuss a more detailed look at how the frequencies and brain waves interact to cause the phenomenon of the binaural beat, and hopefully explain in more detail what is actually happening.
The human auditory system works on a series of signals, frequencies and time differences which are sent from each ear to the brain. The brain analyses the small differences in time and frequency and sends a signal back which results in sound localization, for example, if someone is calling you from another room, the process of analysis will then tell you the location of the person calling to you. These time differences and frequency ranges are called critical bands.
Depending on the frequency of the sound the signals are evaluated from inter-aural phase differences between the signals from each ear. Frequencies which are below 1000 Hz are evaluated by the inter-aural phase differences which are delivered by both ear signals and the sound is also evaluated on the same signals.
When you have two different pure tones playing into each ear at the same time the time dependent phase and differences are what cause the brain to react in different ways, which is a direct result of the different frequencies that are played into each ear and therefore the sound that you perceive to hear.
The phenomenon of the binaural beat happens when the difference in the frequency between the ear signals is lower than a few hertz (Hz) as your auditory system follows the changes in the inter-aural time differences and perceives the third sound to be moving through the head. When the difference in frequency is more than 30 Hz the auditory system is no longer able to follow the changes and an overlay between both signals occurs.
When the frequency difference between both signals is greater than 30 Hz we have what is referred to as the cocktail party effect where the auditory system is able to recognize both sounds individually and identify them as originating from two different locations. This is best explained if you think of a party where you are listening to music and talking to a friend at the same time, both your conversation and the music would be above 30 Hz and that is where your auditory system will distinguish between both signals.
There have been numerous studies which have proven that the binaural beat is associated with the electroencephalographic (EEG) as the auditory stimuli has a frequency – following response which originates in the vertex of the human brain and corresponds to the frequency of the stimulus. The vertex of the human brain is situated at the top of the head. The phenomenon of the binaural beat which is stimulated in this manner appears to encourage access to altering your conscious state.