Entrainment is a principle of physics called sympathetic resonance. This refers to the ability of one thing to affect another through some form of energy. An example of this is sound resonance. If a tuning fork is struck and then placed within the vicinity of another tuning fork, the second tuning fork will begin to oscillate at the same frequency and amplitude as the first. In short, the first tuning fork has “entrained” the second.

The concept of entrainment can be applied to the mind as well. Brainwave entrainment refers to the brain's electrical response to rhythmic sensory stimulation, such as pulses of sound or light.

Brainwave entrainment technology alters the brainwave frequency patterns, which induce various cognitive states. The brain is influenced by repeating stimuli. When given a constant rhythmic stimulus, that rhythm, over time, is reproduced in the brain. The synchronization of the external stimulus and brain can be seen in electroencephalogram captures of brainwave activity.

For example, if the brain is subjected to a pulse of 10 hertz (cycles per second), the brain will eventually adjust to match that frequency-see Figure 2.

The effects of entrainment are both short and long term. Research has shown that on average, when exposed to audio stimulus, the mind will entrain in less than 15 minutes. However, when the entrainment is repeated time and time again, eventually the mind will “reprogram” itself to function at the same frequency without the aid of the sound.

Popular uses for brainwave entrainment include:

• Reducing Stress
• Enhancing Concentration/Focus
• Increasing Energy
• Enhancing Creativity
• Promoting Sleep or Deeper Sleep
• Achieving Calm
• Reaching Meditative States
• Effecting Mood and Emotions
• Improving Sports Performance
• Effecting emotional well-being
• Increasing physical well-being
• Aiding Meditation
• Recognizing & Changing Bad Habits