Gnaural is a multi-platform programmable binaural-beat generator, implementing the principles described in October 1973 Scientific American, Gerald Oster, "Auditory Beats in the Brain."
There has been considerable research done on the subject since that publication, and Gnaural's Windows-based predecessor, WinAural, has been used as the audio stimulus in at least one published study, "The Induced Rhythmic Oscillations of Neural Activity in the Human Brain", D. Cvetkovic, D. Djuwari, I. Cosic (Australia), from Proceeding (417) Biomedical Engineering - 2004.
The central finding of Oster's article: brain activity can be entrained to the auditory beat frequencies created when each ear is presented simultaneously with tones of slightly offset in frequency. My interest has been exploring how this effect (known as "frequency following response" or "brainwave entrainment") can be used to explore mental states, ranging from profoundly meditative to highly alert.
What are auditory binaural beats?
In 1839, German experimenter Heinrich Wilhelm Dove discovered that playing two tones simultaneously, one in to each ear, induced the perception of a "beat frequency" when the tones were of slightly differing frequency (generally less than 100 Hz apart).
While an acoustic mixing of the two tones will also produce a beat frequency, what is notable about auditory binaural beats is that there is no acoustic mixing of the tones: the beats exist solely within the auditory system. Some researchers believe that they are an artifact of the "neural wiring" used to spatially determine the origins of sounds in our environment.
Gerald Oster's breakthrough in 1973 was to observe that the neural processing associated with binaural beats can induce an overall entrainment of brainwave activity (essentially, an oscillation between the two hemispheres in sync with the beat frequency). The neurology of this phenomenon is, according to Oster, tied to the contralateral integration of auditory input taking place in the superior olivary nucleus in the brainstem.
My main interest in the principle has been the possibility that brainwave entrainment can be used to target specific mental states. Gnaural has a long lineage, starting with a DOS program in the mid 1990s, progressing to WinAural for Windows and (in the hope a making a cross-platform solution) BrainJav for Java, and finally the truly cross-platform solution in Gnaural. In over a decade of experience with the technique, I have mainly found it useful for slowing-down brain activity. In that capacity, it has served me in areas ranging from stress reduction, sleep make-up, and particularly as a sort of "poor man's meditation", requiring almost no effort to achieve states of mind that I usually have found rather hard to achieve with real meditation.
But these are strictly my observations, and I make no guarantees about what the technique can do for anyone else. Some of the more unusual applications I've heard about for my software include sustaining a heightened mental focus for online tournament gaming, and enhancing flotation-tank and related sensory deprivation environments. Many people also apparently use the technique to study more effectively.
One of the stranger facts regarding binaural beats is their seeming ability to be equally-at-home in the laboratory setting as in "grass roots" contexts (such as alternative medicine and the New Age phenomenon). That there is a grass-roots enthusiasm (easily demonstrated by googling 'binaural beats') is probably related to the sense of promise inherent in an easy-to-implement technique offering the possibility of direct influence of brain behavior. But from a scientific standpoint, there is a big gap between claims (of what binaural beats can do) and corroboration (by scientific method), which has led to a sense in many that the actual subject of binaural beats is "controversial." But this is an irrational response, given that the actual scientific/laboratory basis of binaural beats has remained an established part of the scientific literature for over 30 years.
One of my goals in writing Gnaural was to implement the binaural beat principle within the bounds of my understanding of the established scientific facts regarding the subject. To some extent, this has meant leaving-out many of the "bells and whistles" prevailent in other implementations. That my software has been used for at least one published "hard-science" study suggests that it has been somewhat successful. However, I also hope that Gnaural proves useful for people who wish to explore subjective areas unfettered by scientific rigor. In a subject dealing with matters of the mind, I see both sides -- "grass-roots empiricism" and "scientific empiricism" -- as being complementary halves of a complete investigation of the possibilities, and ultimately, I'd hope to see the two sides of our culture be catalysts for each other, rather than inhibited by a mutual antagonism.