Inside a light&sound mind machine

These consist of a pair of opaque goggles with built-in flashing lights, and normally a pair of headphones with synchronized beeping sounds. Studies have shown that if the flashing lights and beeping sounds start at something close to your current dominant frequency and then slowly change the "beat frequency" it "entrains" your brain to the desired frequency. So for example, if you entrain to alpha frequencies, you experience some of the same benefits as experienced meditators. Additionally, almost all users report some kind of hallucinations from the flashing lights; mostly colored moire patterns, but some people see detailed hallucinatory scenes. And, of course, many of the same effects as hemisynch can be achieved by the sound synthesizers in a light and sound mind machine. Alternatively, most of the better light and sound mind machines include sound inputs so you can mix the headphone synthesizers with your choice of music, environmental, or HemiSynch-like tapes or compact disks. The main application of these machine is to relax or to tune on a particular mood.

On the surface of it, a light and sound mind machine looks like a pretty simple gadget, just a flashing light(on the googles), some headphones and the case.  What could be so difficult about building one, and why are they so expensive($200 to $10000 and more)?  Actually, the best light and sound mind machines have more features than just a blinking light.  Let's start with the essential features:

• Precise frequency control:  The single most important feature of a light and sound mind machine is the ability to specify the precise frequency that you desire.  At a bare minimum, you should be able to specify this to the nearest half Hertz(Hertz = cycles per second); accuracy to the nearest hundreth of a Hz is to be preferred.  It should handling blinking down to at least 4.0 Hz, and preferably down to 0.5 Hz.  It should handle blinking up to at least 18 Hz, and preferably 25 Hz or more.
• Evenly lighted field:  The more light sources per eye, the better the effect overall.  The original Synchro Energizer uses four bulbs per eye, plus one for the "third eye" placed on the bridge of the nose.  The Mind Gear Innervision PR-1 and PR-2(leading products on the open market - 1990) also have four LEDs or four bulbs per eye. Several machines have three; some cheaper machines have only two. Having only a single bulb or LED per eye is a warning sign that the machine is almost certainly a piece of crap.  The good brightness control is an important feature, too.
• Frequency Following Response (FFR):  These machines modify the brainwaves by starting at you current dominant frequency and gradually transitioning you to another frequency.  To do that, a light and sound mind machine must have some kind of timer, and an ability to specify starting and ending frequencies.
• Basic sound features:  In order the light&sound mind machine to be true, it has to have some kind of tone generator pumping tones into a pair of headphones.  The tones will beep for the entire time that the lights are lit.  At bare minimum, the machine should produce comfortable simple beeps, and give you control over the pitch and volume.  And it really ought to generate binaural beat frequencies, where the difference in pitch between the left and right speakers is equal to the beat frequency in Hz.
• Gentle fade out:  At the end of a timed session, the light intensity and sound volume should fade out gradually.  This feels much better than being dumped out abruptly.
• Automated beat frequency tricks:  You can do a lot more with a light and sound mind machine if it can play seperate frequencies into seperate hemispheres of your brain (left eye with right ear, then vice versa).  Interestingly, small differences in frequency, 0.5 to 1.0 Hz, can make a big difference in the quality of the visuals.  Also nice is the ability to set the left and right hemisphere to the same frequency but 180 degrees out of phase; this has the same entrainment effect but feels different.  (Switching from one to the other and back during a session can help keep you attentive, and keep your mind from drifting off of the frequency.)
• Better audio:  A good thing is the ability to plug in an external audio source and have it mix with the audio beats.  This lets you use mind altering tapes, like HPP, Paraliminal, or subliminal hypnosis tapes while running a mind machine session.  Sound effects are nice, too, particularly the ability to generate "pink noise" (gentle, pleasant static) and a simulated (or digitized) heartbeat, but these are luxuries. For extra power use 21 speakers DCS6 stereo with strong subwoofer system.(What is this? - This is able produce strong clean bass sound in some special environments and this causes the bones of the body to vibrates with the same frequency as the specified by your machine, it also could be projected 180 degrees out of phase)
• Ganzfield effect:  Some people like the ganzfield effect (continuously on, lighted but blank field) for itself, as a meditation aid.  There are rave reviews about using it with sensory deprivation.  If you do intend to use the ganzfield effect, then consider two other optional features. First of all, audio sound effects like pink noise, a "wave generator," and/or a heartbeat may add a great deal.  Secondly, consider getting a unit with incandescent bulbs so you can use gel filters to change the color of the lighted field.  (This is the only known reason to prefer white incandescent bulbs to LEDs.)
• Lots of useful predefined sessions:  It can save you some work if the unit has a simple way of picking a predefined session off of a menu or list, saving you the effort of remembering and specifying the target frequency and duration (as well as any other effects; see below).  If a unit has preprogrammed sessions, there should be at least one beta, several each for different levels of alpha and theta, and at least one delta.  More variety is better, of course.  It's also nicer if some of the preprogrammed sessions can make more than one "ramp" from frequency to frequency.

The new models available also support the following features:

• Pulse and shape control:  Most machines use a 50% on, 50% off square wave for light intensity and sound volume.  Some companies claim that at low beat frequencies, a sine wave or triangular wave would be better. Also, if you are using a square wave, the percentage of each cycle that the light is lit can make a big difference in the visuals.  (This is the only known reason, except maybe battery life, to prefer LEDs over incandescent bulbs. Light bulbs can't go much below 40%, and some companies report best results down around 15%.)

The left diagram shown 50% on, 50% off square wave for light intesity at frequency=1/(2*0.05)=10Hz.The right diagram shows more complex shape of the light signal - sinusuidal.

• User programibility:  The ability to progam your own sessions is a very important factor that makes abailable some advanced features like replaying and mixing some particular sessions. It is common the device to use a PC interface, so it can use the might of its programming environment.
• Compatibility with electrical stimulation:  Strictly speaking, ever since the Light & Sound Turbocharger became available, all light and sound mind machines are electro-stim capable.  But there are several units that combine the a light and sound machine with an electro-stim machine.  If the features that you want are there, the price may be right.
• Biofeedback:  So far, none of the regular light and sound machines doubles as a lucid dreaming reinforcement device, with their ability to detect REM sleep.  They have enough hardware in common, though, we can expect sooner or later one will.  In the meantime, though, both of AlphaLabs units can be connected to an EEG that reads your dominant frequency and adjusts the light frequencies to "lead" it gradually in the right direction, which should make for much more accurate entrainment. Look for other manufacturers to follow suit.

Recently the new types of glasses became very popular - TruWhite, CoolBlue. These don't use just bulbs or LEDs. They make great colors, very fast image changing and reliable interface.

Here is how a commercial of such a machine sounds like:

*  50 preset programs * 'Fill in the blanks' programming  *  Complete manual control *  Design and store up to 25 additional     personal programs  *  Dual light and sound ports  *  Standard Red or Green Led glasses  *  Optional full spectrum 'TruWhite' Leds  *  Pause function  *  End of session 'gentle off' feature  *  Frequency range 0.1 to 42 Hz. *  Independent left / right pulse rate  *  Three digit LCD function display *  Manual pulse width adjustment  *  Dual Binaural beat frequencies  *  Eight tone selections  *  Six light & sound stimulation  modes

*  Connect to your PC with RS232 cable *  all controls are computer programmable *  High quality stereo headphones  *  7.83 Hz. Schumann frequency  *  Internal rechargeable battery  *  AC adapter  designed for 120 volts U.S. *  Carrying, storage case included  *  Complete operating instructions  *  External stereo input jack  *  PolySync tape with 26 sessions   * 100 built-in preset programs *  2-user ready *  Microphone input with volume control *  Easy thumbwheel light and sound control *  Includes all regular  features

How do I know how to configure the device?

All products come with a complete instruction manual including the list with the functions of the frequencies the device can deal with(in our example 0.1 to 42 Hz). A common form of this list is - "4-12Hz of the predefined program 'Quick prestudy' increases concentration". It's impossible to say what is the effect of using some frequencies because the new models have these predefined programs(for example the user can see a rotating triangle(the predefined program) blinking with 10 Hz(the frequency)).

How do these machines affect our topic?

It is very easy for the experts in the field to configure such machine to make you more suggestible. Actually most studying predefined sessions do exactly this thing - they try to write directly to the memory without any conscious involvement. If you have read the Dick Sutphen's introduction to the brainwashing many sects organize their meetings in large rooms with good sound and light equipment - it works in the same way, like a giant light&sound mind machine.

Some of the companies dealing with such stuff are:  Synchro Energize(R), Cerebrex(R), Comptronic(R) Devices(R), InnerQuest(R) and AlphaLabs(R)