Isochronic Tones are an effective method of brainwave entrainment.

They are short sounds which are repeated in quick succession. They are equally spaced and of equal length and volume. The speed is dependent upon the frequency of the targeted brainwaves. To induce a state of relaxation, for example, both brain hemispheres must be synchronised to the Alpha frequency, which is around ten Herz. This means that the impulse signal must be repeated ten times per second.

Does listening to isochronic tones have any effect on the management of pain, or as a treatment modality for SAD – Seasonal Affective Disorder? This article looks at these questions critically but supplies links to clinical studies that indicates that the potential of brainwave entrainment as a medical intervention is grossly neglected.
Source: Living Flow
Writer: Michael H. Thaut
Source: New York Academy of Science (2003), 999: p. 364-373

By looking deep into the cortical and subcortical networks of the brain, the researchers managed to uncover further insight of brainwave entrainment. They linked rhythm and music directly to the cerebellum but also had some major limitations to their findings. They found out that rhythmic processing is following multiple parallel neural computing processes. Therefore, only a professional team can and should create and sustain a complex experience, which holds the scientifically proven benefits to the mind and the body.

Writer: G. Papagiannakis, E. Argento, E. Baka, M. Maniadakis, P. Trahanias
Source: Foundation for research and technology – Hellas (FORTH) Institute of computer science, Technical Report Nr. 458

The study acknowledges the hypnotic effects of binaural beats, but states that they are less effective in achieving brain entrainment. Isochronic tones, however, seem to be more pleasant and enjoyable to the ear and stimulate – with their dynamic repeating sounds – the brainwaves just right to achieve an entrainment effect.

Writer: Tina L. Huang, Phd. Visiting assistant professor at the Ohio State University at Newark Department of psychology, research director at Transparent Corporation.
Source: Alternative therapies in health and medicine, September/October 2008, link from Inergy Mind Spas.

This scientific review by Tina L. Huang, Phd. professor at the Ohio State University suggests that BrainWave Entrainment (BWE) is effective in several cognitive domains and can relieve acute and long-term stress, reduce pain, headache, migraines, and PMS and improve behaviour.
While preliminary evidence does not confirm the desired level of effectivity in all of the examined areas, the study concludes that BWE is worthy of further consideration by clinicians and researchers as a therapeutic tool.