While Lux is a synthesizer, it’s not the kind of instrument you’d play with a keyboard – although that is possible. It should be thought of as “blinking” generator. It is constantly sending out signals: audiostrobe (which is a nearly inaudible, high-pitched tone which controls your AVS machine’s light goggles), noise, binaural beats, and either a loaded WAV file or other audio piped in from your DAW. The guts of the plugin deal mainly with turning these signals off and on to create pulsed signals to which your brainwaves may become synchronized. Let’s look at audiostrobe signals as an example.
Audiostrobe is the specification for the signal that controls your AVS machine’s LED goggles. If you were to send a pure sine wave tone with a pitch of 19.2 kHz to your AVS machine, it would make the LEDs in your goggles light up brightly. If you turned down the volume of that tone, they would get dimmer and dimmer. Likewise, if you raised the volume, they’d get brighter and brighter. Audiostrobe uses two signals; one in the left channel and one in the right. AVS machines that support more than one color (such as the Mindplace Procyon) let you choose which colors correspond to each channel. Mine is set up with the red LED listening to the left channel, and the green & blue LEDs listening to the right. Lux controls these audiostrobe signals by modulating their volumes with various waveforms.
The graph above represents volume over time. The sine wave gradually curves from full volume to zero volume and back again. The pulse (square) wave abruptly switches from full volume to silence and back. Understanding that your AVS machine translates the volume of the audiostrobe signal to the brightness of the LED, you can see how using different waveforms on the light signal would give you different “blinking” visual effects. These same waveform concepts also apply to the other modules in Lux, only you should think of the waveforms as modulating volume, not brightness.
The pulse wave may seem boring, since all it seems to do is turn off and on. In fact, it is one of the best waveforms for brainwave entrainment (see isochronic tones below). One of the things that makes it special is a parameter called pulse width (AKA “duty cycle,” as labeled in the image above). For each cycle of the waveform, you can also define how long it stays on vs. how long it stays off. Playing with pulse width makes some very cool visual effects, and it sounds great on audio modulation as well.
If you modulate the light or audio signal at the right speed, your brainwaves can eventually begin to synchronize to that same rate. A lot of design went into giving you plenty of control over the modulation speed so that you can achieve the entrainment results you desire. The rates of any of the LFO modules or the Binaural Beats may be set manually, or they may be synchronized to a number of sources, such as your DAW’s project tempo, the clock module, or even another module. In fact, you can set up very complex synchronization relationships. For instance, you can set the clock module to slave to your DAW’s tempo, resulting in a modulation rate of 9 Hz (a nice alpha rate). Then, you can set other modules, like the noise LFO, to modulate at 1/2 of the clock’s rate (in this case 4.5 Hz), and the Audio LFO at 2 times the clock’s rate (18 Hz). Once these relationships are set, they stay set. You can slow down or speed up the project tempo, and the Noise and Audio LFOs will slow down or speed up along with it, always preserving the 1/2 and 2x rate relationships respectively.
Imagine that your red and green LEDs are flashing at exactly the same rate – both turning on and off at exactly the same time. The LEDs are in phase. If you slow down the green LED for a little while, then bring it back up to the same rate, it’s unlikely that the LEDs will be turning on and off together anymore. In other words, while they may be blinking at the same rate, the red one is now turning on a little before the green one. The LEDs are now out of phase. How much the LEDs are out of sync is called the phase offset. Phase offset is measured in degrees. Most of the LFO modules in Lux give you control over this parameter, with a range from -180 to +180 degrees.
Lux’s brain is also programmed to keep all the various modules which are synchronized with each other in perfect phase. Most of the time, after you synchronize a module’s rate to another source, you’ll want it to be in phase with that source. In the background, Lux has a dedicated phase clock which constantly outputs little reference pulses to which the modules may synchronize. Sometimes, a module has to wait a while for the sync pulse to come along, and then at that point, it “jumps” into phase. You might hear this jump as a slight glitch in the audio. I wish I could find some way to avoid it, but until it’s figured out, the best thing to do is to anticipate it and design your sessions in such a way that they’re minimized.
“The sensation of auditory binaural beats occurs when two coherent sounds of nearly similar frequencies are presented one to each ear with stereo headphones or speakers. The brain integrates the two signals, producing a sensation of a third sound called the binaural beat. For example, if a frequency of 100 Hz is played in one ear and 107 Hz is played in the other ear, a binaural beat of 7 Hz is created by the brain. Brain waves match or “follow” the binaural beat. If the binaural beat is 7 Hz, an increase in brain waves of 7 Hz occurs.” – Monroe Institute
Binaural beats have 2 components: a base pitch (which is the audible pitch of the sine tones), and a beat rate, (which is the amount, in Hz, that these pitches are offset in each ear to generate the beating sensation). Lux has a dedicated binaural beat generator which gives unique control possibilities for each component. You can even play it with a keyboard.
“Isochronic tones are regular beats of a single tone used for brainwave entrainment. Similar to monaural beats, the interference pattern that produces the beat is outside the brain so headphones are not required for entrainment to be effective. They differ from monaural beats, which are constant sine wave pulses rather than entirely separate pulses of a single tone. As the contrast between noise and silence is more pronounced than the constant pulses of monaural beats, the stimulus is stronger and has a greater effect on brain entrainment.” – Wikipedia
Basically, Isochronic Tones can be achieved by modulating audio volume with a regular waveform. The Audio, Noise, and BB (Binaural Beats) LFOs can all be used to create this effect. For best results, use the pulse waveform.