They are a useful and effective tool that allow you a structured means in which to entrain your brain into a desired, new brainwave state using an intended set frequency range of the audio track. Frequency ranges for desired sleep, recovery and deep meditation states to different/higher frequency ranges for performance “flow-states” and high-level focus and calculation.
Targeted hemispheric changes: Some speculate that specific alterations in brain waves can be made on an individual basis. In other words, you can target one frequency in one hemisphere (via the right ear) and another distinct frequency in the other hemisphere (via the left ear). The left ear affects the right hemisphere and right ear affects the left hemisphere.
I can offer a hypothetical--however do not know know practical it will turn out to be. There is a fair amonut of bad science on this topic on you tube. The gamma wave frequency is associated with attentional focus and arguably a unified sense of self. If it could be entrained it should lead to a meditative focus-like exceptionally well-trained meditators. Some but not all studies on meditating Buddhist monks suggest this is so. Does this really and more generally occur--I will say there is nothing lost in trying--we all go into a 40Hz range on occasion without ill effect-- but I would not put confidence in the purported methods out there at present. Good luck.
1. Compressed formats like MP3 do not retain the sound quality necessary for the brain to fully achieve brainwave synchronization – and are too inferior to effectively deliver even binaural beats downloads or isochronic tones properly, much less something as powerful as NeuralSync™. Our lossless audio entrains at the precise level guaranteed to induce the most potent response.
A popular opinion in the brainwave entrainment community is that listening to isochronic tones without music produces a much stronger effect.  However, in the study by Doherty, Cormac. “A comparison of alpha brainwave entrainment, with and without musical accompaniment” (2014),  it was concluded that brainwave entrainment was equally effective for isochronic tones, both with and without music.
Both brainwave entrainment and neurofeedback deal with brainwaves, but the similarity stops there. Entrainment pushes your whole brain into a pre-determined state, while neurofeedback teaches you how to move specific parts of your brain on your own. It is the differeence between forcing the brain into a given position, and skills building so you can move it there yourself.