Many people will already be aware of the technique of playing different frequency tones in each ear (with headphones) and the perceived Binaural Beats that result, however that is not the only way to create Binaural Beats.
Here is a method for embedding Binaural Beats in any kind of music or sound!
Theory
Playing two tones e.g. 400Hz and 440Hz together will result in an interference pattern at 40Hz
This can be seen in Fig 1
400Hzand440Hz.png 188.27KB
10 downloadsIf the two tones are played separately into each ear then there is no "physical" interference pattern, but it is still perceived by the brain.
What is the problem with this - simple, I don't like listening to constant tones I find them annoying.
Sure, you can add white pink or brown noise or music on top, but why not put the binaural beats directly in the thing you want to listen to:
Bode Frequency Shifting
Frequency shifting is often referred to as Bode frequency shifting in honour of the man who developed it for the Moog synthesizers, and to differentiate it from pitch shifting which usually refers to transposing music up or down.
Frequency shifting moves all frequencies up or down by the same amount e.g. moving every pitch up by 40Hz
Figure 2
40Hz-Crystallize.png 181.79KB
10 downloads shows a excerpt of Lindsey Stirling's Crystallise:Converted to mono, then one copy shifted up by 20Hz and the other shifted down by 20Hz (for symmetry)
The third track shows the interference pattern if the left and right channels are mixed, which has a frequency of 40Hz
Obviously, the binaural beats are slightly harder to detect, both aurally and by looking at the waveforms, but that is the whole point.
They are supposed to be detected subconsciously and not be too obvious.
How to do this
Audacity!
Steve Harris' LADSPA plugins package includes a bode frequency shifter LADSPA plugin.
If you are using Ubuntu or a debian variant, then the package is called swh-plugins
All you need to do is:
(1) Create a mix of music or a track of noise (I prefer brown noise)
(2) Render it to mono if it is stereo music
(3) Make a duplicate of this mono track
(4) Bode frequency shift one track up by half of your desired binaural beat frequency
(5) Do the same for the other track, but shift it down
(6) Set one track to "Left" and the other to "Right"
(7) Export the track in your desired format: ogg, mp3, etc.
(8) Listen to it! (Wearing headphones!)
Note: frequency shifting does make music sound a bit strange, but I find I get used to it after a few minutes... noise on the other hand still sounds like noise
I did all this in Ubuntu, but it should work in a similar way on Windows or Mac too.
