GnauralWhat is Gnaural?
Gnaural
is a multi-platform programmable binaural-beat generator,
implementing
the principle of binaural beats as described in the October 1973
Scientific American
article "Auditory Beats in the Brain" (Gerald Oster). There has been
considerable research
done on the subject since that publication, and WinAural
(an early version in the Gnaural lineage) was used as the audio stimulus for 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 theme of Oster's article is that processesing of auditory binaural beats bears distinct differences from that done for normal sound, emphasizing different neural pathways and highlighting different parameters of the sound stimulus.
Oster's observations inspired a wave of research in to the ways in which binaural beats could affect the brain. One area of research explored how binaural beats could evoke a "frequency-following response" (also known as "brainwave entrainment") in EEG measures. My personal interest in binaural beats has centered almost exclusively around exploring this entrainment potential as a means of facilitating meditative states. However, Gnaural was designed to be neutral with regard to any hypothesis or application, relying strictly on the fundamental findings as described in Oster's 1973 overview.
What are auditory binaural beats?
In 1839, German experimenter Heinrich
Wilhelm Dove discovered
that illusory "beats"
are perceived when pure tones of slightly different frequency
are separately and simultaneously presented
to each ear. Dove's insight was to realize that since there is no
acoustic mixing of the tones, the perceived beats must exist soley
within the auditory
system, specifically that part which processes binaural (e.g.,
"stereo") sound.While research in to binaural beats continued after that, the subject was largely viewed as no more than a scientific curiosity. Oster's paper was landmark not so much for its laboratory findings, but in how it tied-together the isolated islands of research since Dove, in a way that gave the subject a renewed relevance to modern scientific questions.
In particular, Oster viewed binaural beats as a tool with cognitive and medical applications. Cognitively, he felt it could be used to explore neural pathways, and also to address higher-level questions, including how we spatially locate sounds in our environment, and our auditory system's propensity for selective attention (e.g., the "cocktail party effect").
Medically, Oster saw potential for binaural beats as a diagnostic tool, both for auditory impairments, and for a broad range of non-auditory subjects. Most notable was evidence Oster showed that a decreased ability to perceive binaural beats appeared to be a pre-onset indicator of Parkinson's disease. He also presented corroborating data correlating subtle cyclical fluctuations of estrogen in women and their ability to perceive binaural beats.
Notable for Oster's thesis (that binaural beats are processed in ways fundamentally different from normal hearing) was the fact that binaural beats are percieved even when one of the two frequencies is below the human frequency threshold, and also when both frequencies are below the human volume threshold. This, combined with the brain data available at that time, suggested to Oster that the processing of binaural beats followed different neural pathways in the brain from other auditory processing.
The publication of "Auditory Beats in the Brain" launched a wave of new research in to binaural beats. The particular avenue that caught my interest was the effect known as "frequency-following response" (FFR), in which features of a brain EEG could be influenced to "lock-on" to the beat frequency of an binaural auditory stimulus.
Broadly, the rhythmic influencing of brainwave activity is known as "driving." And while binaural beats have no monopoly as an auditory driving stimulus, they do have the unusual property of being able to deliver direct auditory stimuli at sub-audible frequencies (below the range of human hearing), by virtue of the heterodyning being simulated within the auditory system.
The reason this is interesting in regard to FFR is that (generally speaking) the spectrum of perceivable acoustic frequencies is well above the frequency spectrum of brainwave activity. Thus, aside from binaural beats, the only means of presenting acoustic driving stimuli is by externally modulating sound (in to waves or pulses whose periodicity falls within the spectrum of brainwave frequencies).
Binaural beats, on the other hand, provide a direct means by which pure acoustic tones can be delivered to directly produce a driving stimulus within the range of brainwave activity. Perhaps even more important (in regard to driving) is that with binaural beats, the driving stimulus arises internally (within the auditory system). This suggests that binaural beats may more effectively induce driving than simple monaural modulation, if only for the fact that the resulting stimuli arises directly within neural pathways that can be measured in the course of gauging brainwave activity.
My interest in binaural beats as they relate to FFR was as a means to target meditative states, by literally "slowing down" brain activity using a non-invasive (facilitating rather than coercing) approach. In that aim, Gnaural has a long lineage, starting with a DOS program in the mid 1990s, progressing to WinAural for Windows, then BrainJav for Java [NOTE: see GnauralJavaApplet for the latest Java version], and finally the truly cross-platform Gnaural solution. In over a decade of experience with the technique, I have found mainly useful in areas of sleep induction and "power napping", and also as a way to bring meditation both within reach (when stress has put it out of reach) and to extend its boundaries over time.
While there are certainly more coercive forms of entrainment (photoic, electromagnetic), binaural beats to me lack their negatives, which include some fairly risky potentials (such as epileptic seizures). Also, my goal with the use of binaural beats has never been to replace meditation, but rather, find a non-addictive, non-reliant means by which to facilitate deeper explorations in to states of mind. Interestingly, because of the "voluntary" nature of the binaural beat approach (i.e., it doesn't "impose", it "encourages" FFR), I've found that the most important ingredient of a session is my intent. As in, the same schedule (usually focusing on a beat frequency range of 3 to 5 hz) can have either the effect of facilitating a deep meditative state, a deep sleep state, or even extraordinary alternative states of consciousness, each entirely depending on which goal I choose to focus on.
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 with the Gnaural lineage 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.
Lastly, much is made in the press and marketplace about an almost mystical power of binaural beats to do amazing things, ranging from "curing addictions" to enabling "out of body experiences." While I pass no judgment on what other people claim they can do with the technique or software, one of my primary goals in making this software was to keep it outside of those arguments, neutral, implementing the binaural beat principle strictly 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. But I hope my approach has also been flexible enough that all interested in the technique can use it. That my software has been used for at least one published "hard-science" study suggests that it has been successful on the laboratory front.
Gnaural is officially opensource, released under the GNU General Public License. It was written with the very popular multi-platform GTK+ libraries (core to Gaim and GIMP and hundreds of other great pieces of software) with the intention of making it portable to all platforms. Currently I've successfully compiled it for Linux and Windows, and am hoping somebody else knows (and cares) enough to make a Mac port too. (Programmers Note: see here for info on the Macintosh possibilities).