^ Trost W. and Vuilleumier P., Rhythmic entrainment as a mechanism for emotion induction by music: a neurophysiological perspective. In The Emotional Power of Music: Multidisciplinary Perspectives on Musical Arousal, Expression, and Social Control, Cochrane T., Fantini B., and Scherer K. R., (Eds.), Oxford, UK: Oxford University Press; 2013, pp213–225.

Aside from Brain Evolution, this is another good resource for brainwave entrainment products that I recommend. They have binaural beats and isochronic tones for many different applications. The nice thing is that they are inexpensive, so you can experiment with different types and find ones that work for you. They also have a membership plan that makes experimenting even more affordable. It’s probably the best bang for the buck that I can find for brainwave entrainment.

Move-Thru-It Strategy: to support optimum recovery rates, use 6-8 pumps or 3-4 droppers. Repeat every 1-3 hours for a day or two (with a good night's sleep). The idea here is a persistent frequency. Once you have achieved initial results, you can switch to more conventional usage patterns such as 3-4 times a day. For example: Kick-Ass Immune, Get Over It
So, there’s the deep stuff here, and then there’s the gamma stuff, too. There’s a little bit of 80 Hz, but it’s primarily a 40-Hz gamma track, gamma frequencies that are combined with a pulse, on and off, throughout the recording. I went to some lengths to make this as rich and potent as I could, whilst blending it into the sound of the music. There are these really rich, kind of cat-purr-like vibrations that come through at times, combined with the lulling, deeply relaxing theta brain waves.
Brainwave entrainment music can be used almost anywhere and anytime, making this mood and self-improvement method versatile and flexible enough to do at work, while traveling, or at other times during the day. When used in the workplace during short rest periods, brainwave entrainment techniques can enhance concentration, communication, and work productivity.
Beta brainwaves are typically those we experience when we are wide awake and full of energy. You can think of this frequency as the equivalent of taking stimulants like caffeine, Adderall, or various nootropics. The Beta frequency is good for generating a concentrated, focused, and analytical mind. In fact, the brainwave you probably possess while reading this is of the Beta frequency.
In addition to its calming physical effects, the relaxation response also increases energy and focus, combats illness, relieves aches and pains, heightens problem-solving abilities, and boosts motivation and productivity. Best of all, anyone can reap these benefits with regular practice. And while you may choose to pay for a professional massage or acupuncture session, for example, most relaxation techniques can be done on your own or with the aid of free audio downloads or inexpensive smartphone apps.
♥ I found the Binaural Beat Machine to be my #1 focus tool. I have ADD/ADHD and am too easily distracted when I really want to focus. I turn on the binaural beats using the 16b preset for focus and turn down the volume so it's just barely present to my ear. I couple it with some classical music and am able to focus on what I want for extended periods. This literally has changed my life. Thank you!!
Brain waves are electrical activity patterns caused by the neurons of the brain communicating with each other. Brain waves can be detected using sensitive medical equipment such as an electroencephalogram (EEG) monitor. Brain waves provide an indication of the mental state of an individual. In other words, the appearance of brain waves is directly connected to what a person is doing, thinking or feeling. The different Brain states are: Gamma, Beta, Alpha, Theta, Delta. You have your own unique brain wave patterns that function habitually. Some of these brain wave habits are useful, and others need some fine-tuning. When your brain is functioning efficiently, your brain waves are “in sync” with your activity, but stress or lack of sleep can interfere with this natural harmonious relationship. To restore this harmony, at Gaia Meditation, we have developed a wide range of free audio programs, including meditation music, relaxation music, sleep music and plenty other Sound Healing programs.

Well … to understand the role entrainment plays in meditation, think of a water pump. Most of you have lived in areas where you have access to city water. You turn the knob on the tap, water comes out, end of story. If you grew up like I did, on a farm with a local well, then you probably know that in order to get the water flowing from a well you must first “prime the pump”. (Those of you who remember the days when cars all had carburetors rather than fuel injectors might also remember running out of gas and needing to prime the carburetor with a little gasoline. It’s the same principle.)
Subsequently, the term 'entrainment' has been used to describe a shared tendency of many physical and biological systems to synchronize their periodicity and rhythm through interaction. This tendency has been identified as specifically pertinent to the study of sound and music generally, and acoustic rhythms specifically. The most ubiquitous and familiar examples of neuromotor entrainment to acoustic stimuli is observable in spontaneous foot or finger tapping to the rhythmic beat of a song.