The Anatomy Of A Binaural Beat Soundscape Pt. 1

Now that we have gotten past some of the most basic forms of entrainment, I want to go over the anatomy of a basic tone containing a binaural beat.

This can be created using mostly any audio editor application. I've typically used Adobe Audition, but feel free to comb this list for other freeware alternatives :

http://open-tube.com/20-free-digital-audio-editors/


Before we go any further, it's time for the 'Standard Disclaimer/Warning' :

I would tread carefully in downloading any of these audio editors. Many of these sites use download mirrors like CNET and Softpedia, so it goes without saying to thoroughly virus-check anything you download before installing it.

Also - always make sure you are selecting the right 'Download' button. A lot of these sites have banner advertisements that try and trick you into thinking their 'Download' button is the real one.

(CNET in particular worries me - it always seems to set off the virus alerts built into the Firefox browser I'm using.)

Okay, now that I have told you everything you already know about the nature of the Internet, let's get back to the topic at hand :

So, let's say you want to make a sound file containing binaural beats to help you sleep. What should it contain?

The Audible Tones

Obviously, the most critical piece of the puzzle is the two audible tones that create the binaural beat. So let's say we want to aim for a binaural beat associated with 5 HZ (which would be associated with sleep). Like I had written in the previous entry, you're going to do two audible tones, one in each ear. The two audible tones should subtract out to 5 HZ.

How do we decide what exact audible tones to use? :

Pitch

While there is some debate over this, a common thought is that binaural beats will not work using audible tones over 1000 HZ. For that reason, you want to aim below that.

There is also a lower cutoff for the audible tones. You don't want to venture too far below 200 HZ with them.

There are a couple reasons for this -- for starters, the tones tend to get more bassy, and this is a mixed blessing for binaurals beats :

On one hand, if you want to smuggle the audible tones containing the binaural beats into music, what better place to hide them than in the bass range, since the human ear is less sensitive to that range?

On the other hand, does the lack of sensitivity humans have to the bass range make the binaurals less effective as a result? One would probably have to boost up the volume on the bass to compensate for this, which leads to the next potential issue.

When trying to incorporate binaural beats into music, generally the lower in audible tone you go, the more impact adding in the binaural is going to have on the perceived note, since there is less space [in HZ] between notes in lower octaves.

On top of all that, there is yet another reason why audible tones in the bass range can sometimes be bad for constructing binaurals, and it involves something we all hate -- math. (Okay everybody, get out your calculators.)

Given the two audible tones you are using to construct a binaural. Take the lesser of those two numbers and multiply that by 16%. That value is the maximum binaural beat that can be created by these audible tones.

For example, say you wanted to use audible tones around 100 HZ to create a binaural. The maximum binaural value that could be supported would be 100 HZ x 16 %, or 16 HZ.

As you can see -- a 200 HZ tone is going to be able to cover most of the gamut of brainwave frequency ranges. (It would be able to accommodate binaurals up 32 HZ, and more often than not, that's as high as you'll need to go.)

Once you start going below 200 HZ (and particularly below 100 HZ), you're starting to limit the binaural beat playing field a little.

Waveform

I believe it has been said that the triangle waveform is best to use for the audible tones comprising binaurals. (I can't remember the exact reason why.) I find I usually stick with sine waves or triangle waves, and use square and sawtooth waves less frequently.


Volume [Amplitude]

I'm calling it volume, even though amplitude is probably the more accurate name. The volume of the audible tones should be comfortable to listen to. Generally, the higher up you go towards 1000 HZ, the less overall volume you need for the tone, since the ear gets more sensitive to sound as you head up that way. If you're using a background sound, it's perfectly okay to let the background sound take the lead volume-wise, while putting the audible tones containing the binaural a bit further in the background.


Panning

I wouldn't do any panning with the audible tones containing the binaural. The short answer is it will probably mess with the binaural functioning.

The long answer is there are probably ways you can incorporate panning into the audible tones that comprise the binaural beat, but it's not an exact science. If you were to have the left and right channels trade places X times a second, at slower panning speeds I'm thinking you'd get something that alternated between a binaural and monaural. At faster panning speeds, you would end up with a monaural, I would think - since the brain would effectively perceive both tones as being in both ears. The more I think about this, the more I want to experiment with this -- the frequency of the panning between the left and right ear itself would have a brainwave entrainment effect itself. It would be interesting to see how the brainwave entrainment effect caused by the binaural interacted with the brainwave entrainment created by the panning itself. If the binaural beat was 7 HZ and the frequency
of the panning was 6 HZ, you might end up with an almost polyrhythmic sort of effect.

Sample Rate

This is getting a little more technical.

Just to give a definition of Sample Rate from WhatIs.Com :

"In developing an audio sound for computers or telecommunication, the sample rate is the number of samples of a sound that are taken per second to represent the event digitally."

Now, it's time for math :

The sample rate of the audio file needs to be at least twice as much as the highest frequency you wish to hear in the sound. For instance, if you want to hear frequencies in a sound in the 4000 HZ range, you're going to need at least an 8000 HZ sample rate.

On the other side of the coin, generally the bigger the sample rate is, the bigger the file size will be.

For binaural beats, since the audible tones comprising the beats will be under 1000 HZ, you should be able to save the file with an extremely small sample rate, which results in a very small file size. I have tested binaurals I've created with sample rates as low as 6000 HZ, and have still been able to perceive the brainwave entrainment effect. (Just to put the 6000 HZ sample rate in perspective, audio from a music CD typically has a 44100 sample rate, and DVD audio can be even higher than that.)

Now, the downside of using low sample rates with binaural beats :

• If you're using more elaborate waveforms with harmonic overtones, you may end up cutting out some of those overtones.

• You're generally not going to create a binaural beat in a vacuum, because naked binaural tones are boring. People need something acoustic to chew on, so you typically will add a background sound of some kind (ocean waves, noise, etc). These sounds will have higher frequencies, and will warrant a higher sample rate. 

This actually serves as a good lead-in to the next section, dealing with background sounds, and how they make the binaurals less monotonous. (If binaural beats are the pill, the background sound is the yogurt you hide it in to make it palatable.)

That will be 'Pt 2', since I'm getting carpal tunnel here. If I do any more typing tonight, I think my fingers will unionize and go on strike. (Although, a horde of striking finger puppets is admittedly an entertaining thought.)