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Rich Decibels disrupts brainwaves using an Arduino August 5
Audio-visual brain entrainment using an Arduino
There are some interesting theories about the ability of low frequency light and sound to alter brain states. I created the Rich Decibels Brainwave Disruptor to investigate some of the theories.
Theory
Electrical activity in the brain is rhythmic. The frequency of this rhythm depends on the state the brain is in: an active, alert state correlates to rhythms in the range of 30-100Hz. As brain activity reduces in frequency, so the brain state changes: 8-12Hz is associated with relaxation, 4-7Hz with meditation, and below 4Hz indicates deep sleep.
The concept behind ‘brainwave entrainment‘ is the idea that you can induce different brain states by causing brainwave frequencies to fall into step with external stimulus.
Concept
My device generates this external stimulus with binaural beats, by creating two tones whose frequencies are separated slightly, along with flashing lights and a pulsating audio filter.
Hardware
The handsome case was designed in Sketchup, and laser-cut in my Personal Factory. The text is engraved and then filled with white-out fluid. Under the hood is an Arduino Uno, and two interface boards I designed.
Board 1 has ‘pitch’ and ’separation’ controls, connected to the Arduino’s analogue inputs. It also has a pair of low-pass filters (one for each channel), whose intensity is controlled by the ‘depth’ control. The filter cut-off is set by a vactrol whose brightness is set using the Arduino’s PWM outputs.
underside | layout | schematic
Board 2 has six transistor circuits to drive the LEDs in the goggles, along with a volume control for the audio.
underside | layout | schematic
Software
There are many ways to generate audio with an Arduino. uC Hobby has a great round-up that goes into some depth about the many different approaches. I personally learn better from real-world examples so I started out by stealing the code from the Nebulophone and paring it down from there.
In the end I settled on a ‘bit-bang’ approach: toggling an output pin High-Low-High-Low at the right frequency to generate rudimentary audio. Here’s the code in its current form if you’d like to have a tinker.
Testing
Astonishingly, it works! At certain frequencies the flashing lights especially have a really eerie effect, generating crisp geometric hallucinations on the inside of my closed eyelids. Something I hadn’t expected were audio hallucinations: its as if the brain gets bored listening to two consistent tones wobble on indefinitely and starts to invent harmonies and chord progressions. My sense of time was thrown out the window, too, with 90 minutes passing in what felt like 20.
On Display
Don’t take my word for it though, come see for yourself! The Brainwave Disruptor is on display at Thistle Hall in Wellington, NZ for a week starting Monday (8th-14th August) as part of The Briefcase Project.
Audio Sample
Health and Safety Warning
This is a potentially dangerous device. In my research I’ve seen claims of between 1-in-4000 and 1-in-10000 people suffering seizures from visual stimulus like this. I’ve not seen any evidence of low frequency audio having the same effect, but you should proceed with caution regardless.
August 5th, 2011 at 10:20 am
Already have the Gnaural program, but your gadget looks nice, too.
August 5th, 2011 at 10:22 am
Nice? Great!
August 6th, 2011 at 8:22 pm
Awesome post, Rich. That case *is* very handsome. Def putting this one in the newsletter. (P.S. You could share this in the Show Off Your Project section on the forums, too: http://support.ponoko.com/forums/345606-show-off-your-project)
August 7th, 2011 at 9:18 am
[...] Whether you believe in it or not, the science behind brainwave entrainment is incredibly intriguing. [Rich Decibels] became interested in the subject, and after doing some research, decided to build an entrainment device of his own. [...]
August 7th, 2011 at 9:23 am
[...] Whether you believe in it or not, the science behind brainwave entrainment is incredibly intriguing. [Rich Decibels] became interested in the subject, and after doing some research, decided to build an entrainment device of his own. [...]
August 7th, 2011 at 11:11 am
Have you tried anything up at 40Hz, there’s a few claims about 40Hz being the frequency which ’syncs’ the brain (Gamma Waves)
August 7th, 2011 at 1:01 pm
[...] Whether you believe in it or not, the science behind brainwave entrainment is incredibly intriguing. [Rich Decibels] became interested in the subject, and after doing some research, decided to build an entrainment device of his own. [...]
August 7th, 2011 at 6:21 pm
You’re 90% of the way to building a BAUD machine (http://www.mybaud.com/intro.html), which has been on my list of things to do for quite a while.
[PDF] Users Guide v4.2 – BAUD Energetics
http://www.baudenergetics.com/Users%20Guide%20v4.2.pdfFile Format: PDF/Adobe Acrobat – Quick View
The Bio-Acoustical Utilization Device (BAUD) is a sound-emitting … adjusted as the user desires. No specific instructions are given for the …
I have some ideas for improving on the BAUD: interested in collaboration?
James
August 8th, 2011 at 5:47 pm
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August 8th, 2011 at 6:06 pm
Any chance you’ll be demoing this in the states?
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August 8th, 2011 at 6:28 pm
Amazing – where can I find longer audio samples?
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August 25th, 2011 at 9:23 pm
[...] Find out more or purchase your building kit at http://blog.ponoko.com/2011/08/05/rich-decibels-brainwave-disruptor/ [...]