A relatively new science that is being applied to meditation is Neuro Acoustics. Here is a definition as posted in the site www.healingmusic.org:
It has long been known that the brain generates electromagnetic signals, which can be detected with EEG (Electro-encephalogram) equipment and that different frequencies are produced depending on neural activity. Neuro-acoustics is the feeding back of these frequencies to the brain through the use of sound waves. Binaural beats are often used as a means of transferring this information in a spatial format to the body-mind.
There are two leading companies in this field for meditation:
Centerpointe Research Institute
Centerpointe Research Institute had its modest beginnings in the fall of 1989. Bill Harris and Wes Wait, both with a long-term interest in meditation and personal growth, had spent the previous four years with a small circle of friends researching and personally experiencing the effects of what later evolved into Centerpointe Research Institute’s Holosync® audio technology.
The idea of using precise sounds to alter a listener’s state of mind came from a 1973 article in Scientific American by researcher Dr. Gerald Oster of Mt. Sinai Medical Center in New York. In this article, "Auditory Beats in the Brain," Oster describes a characteristic of the brain wherein electrical brain wave patterns resonate to certain precise frequencies when presented with audio tones of certain frequencies.
After their four years of personal experimentation, during which those in the research group experienced what could only be described as profound mental, emotional and spiritual changes, Harris and Wait decided to create a structured method for using Holosync, and in 1989 they began marketing this program to the general public. With electronic tone generators and frequency counters borrowed from a local university, the master soundtracks were recorded for a series of 13 program levels, each more powerful than the last.
The initial idea was to re-create, with modern high-tech methods, the meditation experience usually reserved to those dedicated few willing to meditate many hours each day for many years. To recreate the second ingredient of the meditation process—the "rescripting" that takes place as meditators reach an altered, meditative state and then reprogram their unconscious mind through mantras, affirmations, or prayers—they added, beginning with the second level of the program, silent affirmations chosen by the participant and recorded in his or her own voice, and delivered using Centerpointe’s proprietary Autofonix® silent messaging technology..
The results were spectacular and participant feedback extremely positive. Participants reported a dramatic acceleration of positive results in their meditation practice, often reporting more change in a single year of the Centerpointe program than in ten or fifteen years of traditional meditation.
Center for Neuroacoustic Research
Dr. Jeffrey D. Thompson, D.C., B.F.A. http://scientificsounds.com/ has been experimenting with sound since childhood and specifically in the healing field of medicine since 1980. He began his clinical research in Virginia in the Holistic Health Center he established there. At the time, the Center was the largest of its kind in Virginia. His experiments used exact sound frequencies to make Chiropractic spinal and cranial adjustments, to stimulate and normalize organ function, and to balance Acupuncture Meridians. With significant success behind him, he moved to Southern California in 1988 to continue and expand his research and interest in the field of scientific sound.
Dr. Thompson is recognized as a worldwide expert in the field of brainwave entrainment frequencies incorporated into musical sound tracks. A consummate musician and composer in his own right, he has established a method for using modulated sound-pulses for Brainwave Entrainment for changing states of consciousness for optimal "Mind-Body" healing. He continues to compose music and soundscapes, to treat patients, to further the use of sound in a scientific manner through on-going research, and to develop scientific sound delivery systems for maximum results. He is an educator and fascinating speaker and speaks widely on the use and benefits of Scientific Sound for stress reduction, relaxation, sleep enhancement, learning remediation and mega-learning, creativity and peak performance, meditation and ecstatic states of consciousness.
"Healing the Body * Heart * Mind and Spirit with Sound"