Analyzing binaural beat CDs, and a tip for BAVSA users

Every few weeks I get a call from a user who wants to import a brainwave entrainment CD or MP3 they bought elsewhere into our program in order to change what frequencies are being used and at what times.

If only it were that easy. Once a composition has been exported from a brainwave protocol into a sound format, it becomes very challenging to reverse engineer that and determine what frequencies are being used.

It becomes even more difficult when you realize that there are many different forms of auditory brainwave entrainment – binaural beats, monaural beats, isochronic tones, audio modulation, filtering and so on. Most commercial products also “mask” the entrainment in some way, usually with nature sounds such as rain, or with music.

Simply determining what brainwave frequencies are used in a recording is hard enough, much less changing or altering those frequencies in some way.

However, some users in our community forum have found a way to do this, at least with recordings that use binaural beats. First, they use a tool called BAVSA to determine what binaural beat frequencies are being used. Then, they use audio filters (band pass) to remove the binaural beats. Later, they re-insert binaural beats of their choice, using our software.

BAVSA, which stands for “binaural beat visual analysis tool”, is a program specifically designed for analyzing binaural beat frequencies. It is the creation of Jim Peters, who also created SBaGen, which I mentioned in a recent article in the AVS Journal.

You can find BAVSA here:

BAVSA is a remarkably accurate program, but can sometimes take some fiddling with to get a clear result. This is understandable, given the complexity of many binaural beat CDs, especially those with music.

Back in June, another user and I analyzed a recording with a single binaural beat that ramped from 10 hz to 2 hz. As the beat and pitch decreased, we noticed something strange: 10 hz remained through the entire recording, and other “phantom” beats showed up in the analysis as a result.

After some experimentation, we discovered that if a binaural beat is present at a high enough volume in the first 3 seconds of the recording, BAVSA’s analysis of the rest of the track will always contain the first 3 seconds of sound.

To show you what I mean, I created a binaural beat that lasts for 5 seconds and then a minute of complete silence after that. You can use any binaural beat program to create this yourself, such as our software, cooledit or SBaGen (all will produce the same result in BAVSA).

Analyzing this in BAVSA, I skip ahead to 48 seconds. It should register silence, but instead it still shows the original binaural beat:

The Solution: To work around this problem, I insert 3-4 seconds of silence at the beginning of any sound file before analysis. We applied this fix to the 10hz/2hz sound file I mentioned above, and BAVSA accurately reported the binaural beat at the exact same time mark, without showing 10 hz or the other non-existent frequencies:

In most cases, this workaround isn’t strictly necessary, since binaural beat CDs typically don’t have tones at a high enough volume for this to matter, and many CDs fade in over 10-20 seconds, effectively eliminating the potential for a problem. This may also explain why this hasn’t been noticed before.

Still, if you want to be absolutely sure of an accurate measurement, try the above tip.

2 Comments to “Analyzing binaural beat CDs, and a tip for BAVSA users”

  1. Marco 29 January 2010 at 8:41 pm #

    Thanks for the post. That piece of advice will help me to decide the buy of brainwave entrainment software.

    In this website you can try free binaural beats to find out if this works with one:

  2. binaural beats 19 May 2010 at 4:54 pm #

    Great Article ! I was going through BAVSA programs and found some really interesting frequencies in many of CDs. For eg.

    frequencies found by bavsa on CD “Orientation Focus 3”:
    it starts with
    3.9 herz (at 300 herz carrier frequency)
    then it changes into
    3.9 (300)
    0 (60)
    and again changing at 23 min. into more complicated
    1.4 (114)
    3.5 (111)
    6.3 (116)
    3.8 (300)

    CD “Super Sleep”:
    1.5 (100)
    49 (74)
    51 (75)

    CD “Cable Car Ride”:
    impossible to read, due to its strange
    and ever-changing frequencies.
    The same goes for CD “HemiSync in Motion.”

    I don’t know if bavsa really does the reading
    and if I read the frequencies correctly.

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