A harmonic is a multiple of what is termed the "fundamental frequency" (original frequency). If f is the fundamental frequency, its harmonics are 2f, 3f, 4f, etc. For example, a fundamental frequency of 12, would have harmonics of 24, 36, 48, etc. Harmonics are utilized in Harmonic Box X to a limited degree, and Nirvanic Mind™ also utilizes them directly in some of our products.
As with Harmonic Box X, harmonics must be carefully contructed with special attention given to the potential effects of each harmonic on the fundamental frequency utilized. This is especially the case in any session for relaxation or sleep for example. If you set a fundamental frequency of 7hz (theta brainwave state) to help you relax, its next harmonics are 14hz and 21 hz, both in the beta brainwave state, which would negate the relaxation response of 7hz, due to the energizing nature of the higher frequencies. Many companies that utilize harmonics of any kind often do not take this into consideration which causes their sessions to be ineffective, or worse yet, having the opposite intended effect.
Nirvanic Mind™ only utilizes harmonics when all of the harmonics support and complement the fundamental frequency.