WHICH:

Audible

Harmonic Superimposition:
Carefully tuned binaural beats are superimposed, layer upon layer, causing different groups of neurons to fire at different frequencies. The Harmonic Superimposition technique provides a number of beat frequencies, and combines them simultaneously so that the beats themselves create harmonic frequencies to drive a highly specific brain state.
Also, this technique has a high signal to noise ratio (approximately 60 dB), and usually goes relatively unnoticed by the audience when placed in the audible spectrum.

Subliminal

Silent Sound Spread Spectrum (S-quad):
Essentially binaural beat entrainment in an area known as the perceivable non-audible frequency spectrum. These sounds lie above the audible frequencies between approximately 20 KHz and 100 KHz, and are most dominant under 50 KHz. These occur within the harmonic frequencies of traditional instruments up to 102 KHz. Often, these PNA frequencies
are responsible for providing the richness and warmth of live sound (analog recordings provide more of these PNA frequencies than traditional digital recordings). Standard digital
technology is capable of producing low level PNA frequencies that lie immediately outside the range of human hearing, 22- 25 KHz, through binaural beat entrainment.

Noise

White Noise:
White noise is naturally present in the human nervous system. Hearing white noise aids in moving between brain states: it can both encourage a trend toward the Beta state when played loudly and a move toward Theta and Delta when played softly.