Advice For Creating Bilateral Stimulation Music
Updated: Jan 2, 2022
Acoustic or auditory bilateral stimulation (also variously known as bilateral stimulation music, Brainspotting music or EMDR music) is the rhythmic swaying of sound between the left and right channel of headphones or earbuds. It is designed to be used for emotional healing and personal growth. There is a great need for more sources of acoustic bilateral stimulation. This article shares suggestions for interested people or companies other than Alternating Sounds, LLC to use when designing or enhancing music with bilateral stimulation.
Over the course of seven years, four albums and countless experiments producing bilaterally enhanced music and "soundscapes", my Alternating Sounds LLC learning curve about what helps improve the effectiveness of this special kind of music continues to this day.
My hope is that others who want to create their own bilateral stimulation recordings will consider incorporating the suggestions from this ever-evolving list of what I consider to be "best bilateral practices".
1. Always use multiple levels of bilateral strengths
Whenever possible, we think it's a very good idea to mix your recording so that the listener is ALWAYS hearing multiple simultaneous bilateral strengths (msbs). (As a reminder to those new to the field, "bilateral strength" refers to the degree to which a sound source travels back and forth between the two channels of headphones or earbuds. Sound that sways all the way to the left and right channels has 100% strength; sound that does not sway at all has zero strength.
Here's why we think that "msbs" is so important: If the music source only has one level of bilateral strength the listener misses a golden opportunity to accelerate neural activation, potentially by orders of magnitude. The brain has the ability to process multiple simultaneous bilateral strength levels, unlike visual (eye movement) techniques. Why not provide numerous opportunities for neural engagement?
We think that if you experimented with a blind comparison of any music from the Alternating Sounds, LLC label with a "single source" bilateral recording it's almost certain that your brain will notice the difference. Music from Alternating Sounds, LLC always has been -- and always will be -- bilaterally enhanced in this manner. We think this ought to be the industry standard and encourage all other companies to follow suit.
Specifically, our basic recommendation is to use three sound sources with varying bilateral strengths as follows:
The strength of the primary sound source should travel on a wide arc left and right (see below for suggested strength ranges). This is the "primary" or "melodic" bilateral strength".
Another sound source (such as a babbling brook or gentle rain) should be simultaneously mixed to about half the bilateral strength of the primary source. We call this the "secondary" or "harmonic" strength.
Finally, a third sound source should be mixed to travel back and forth just a few degrees (less than 10%) from the center of the sonic field. Examples of this "stabilizing" or "subtle" strength can be anything from a bird song to a specific frequency.
Again, the point of these multiple simultaneous bilateral strengths is to give the brain the most positive activation possible. The opportunity is there: use it!
2. Avoid Excessive Bilateral Strength (BLS) Ranges
After the 2014 release of the first Alternating Sounds, LLC album, "Written on Clouds",
it became apparent that the panning strength on several tracks was less than ideal for some purposes. Out of this came the realization of the need to be cautious to not overdo. While there is a limited place for full or near-full bilateral strength (bls), it generally seems neither necessary nor effective to set primary strength levels beyond 75 - 90%.
One reason for avoiding full (100%) bls is that doing so results in each ear sequentially experiencing the absolute momentary absence of sound, over and over again. It just doesn't seem sensible to ever completely cut the auditory relationship between the hemispheres. It's like dropping one end of a jump rope or cutting one of the cords holding up a hammock: both fall and thus fail their purpose. The ears need to be hearing the same sounds at all times, no matter the ratio between them. Without some auditory connection at all times each ear will alternately experience isolation and then flooding.
One of the few exceptions that actually benefits from 100% bls is when a single percussive sound switches between sides in a binary fashion like an on-off switch. One such early recording is the 1996 release of Robert A. Yourell's Up-Level: EMDR-Inspired Stable Bilateral Soundspace. It's just 45 minutes of a single bell-like tone that shifts between the ears at at about 80 cycles a minute (cpm). As the Amazon reviews, people wither loved or hated Up-Level. I found it very useful when writing in public places like coffee shops. Ordinarily I find nearby conversations very distracting, and the continuous 0/100% alternation was so useful in focusing my attention on the project at hand that I would be surprised when the 45 minutes were over.
Anyway, back to the present. I'm now clear that mild to moderate panning strengths are very effective. Strengths that are less than 50% seem to provide a stabilizing or calming effect and therefore seem useful for integration or consolidation of gains. On the other side of the spectrum a bls over 75% tends to evoke more stimulating or accelerating neural engagements. Both can be very useful at times.
The use of multiple simultaneous bilateral strengths, discussed earlier, combine strong, mid-range and mild strengths in a way that seem to bring out the best in each range.
ln mixing, when in doubt reduce bilateral strength. With a practiced ear you'll notice when the arc leads away from a solid sense of stability necessary to really lean into the activation process.
Experience shows that the brain is going to begin to get fatigued if the bls is excessive. So I'm convinced of this: In mixing, when in doubt, reduce bilateral strength. With a practiced ear you'll be capable of noticing when the bilateral arc leads the listener away from a solid sense of stability necessary to really lean into the activation process, especially with three simultaneous strength sources.
Every piece of music on the Alternating Sounds, LLC label has been carefully, lovingly -- even obsessively -- calibrated. On most recordings the bls is constantly adjusting slightly one way or the other. There's a lot going on in even the most simple soundscapes.
I'll end this section by saying that "Written on Clouds" has some useful tracks for clinical application, while others are less useful for therapeutic uses because of excessive bls (as well as excessive cpm, which I'll cover in the next section. The second album, "From Old Illusions to New Conclusions" was specifically tailored for use in Brainspotting and other clinical applications. I mixed it in consultation with several Brainspotting experts worldwide. The selections are longer (several over 10 minutes), the sonic field is active yet very stable, and the strengths typically range from very mild to moderate. In additions, the cycles per minute (cpm) are generally as slow as possible while still engaging the bilateral effect.
Confused about cpm? The next section is for you!
3. Be Mindful of Cycles Per Minute (CPM)
A key element of any form of bilateral stimulation (whether tactile, visual or acoustic) is the length of time it takes for the stimulation to achieve one full (left-right-left) cycle. These are known as cycles per minute (cpm) and they are a vital consideration when producing your music.
The general rule of thumb is to use slower rates for resource enhancement, integration and consolidation purposes and faster rates for entering into the heart of the work.
(While on the subject, some experimental recordings on the Alternating Sounds, LLC played around with ultra-fast cycling. One extremely intense example was taking the Daft Punk song "Contact" and applying a cpm rate somewhere in the 300's. I don't have the exact cycling rate in front of me but it was mixed to exactly match the speed and intensity of this powerful album closer. I nicknamed is the "Mental Dental Drill" for the very powerful effects it always had on me. Of course, since the music belongs to Daft Punk, not me, it was just an experiment for my own purposes and never offered commercially.)
But I digressed again. The main point here is to keep the cpm slow to provide a stable/neutral platform for clinical settings like Brainspotting or personal emotional development. Think: "slow is stabilizing and fast is activating." For overall processing, keep it to what I call "conveyor belt speed": 4 to 12 cpm. Yes, this means that I am advocatng such a slow cpm that it takes 15 seconds to complete one cycle (and again, with only gentle to moderate bls.)
4. Always "Ramp" On and Off
I use the term "ramping" for the process of starting and ending any bialteral recording at zero strength. In other words, start and end with the listener being to "step on and step off" the session at the exact center of the sonic field.
In my opinion there is absolutely no justification for starting or ending a bilateral soundscape at full strength. It's muck more gentle and respectful to give the listener an opportunity to "settle in" before the swaying/panning/bls (all terms for the same process) begins to intensity. Likewise, take 30 to 60 seconds to gradually reduce the strength until the listener "steps off" before removing the headphones/earbuds. It's think that ending with full bls is neither respectful or unnecessary. Imagine coming off a carnival ride, either a relatively gentle merry-go-round or, especially, an intense roller-coaster, before both have stopped completely.
To emphasize, don't force the brain to immediately jump into and off of the bilateral engagement. Take it slow both ways. Begin and end at the center of the sonic field. It can help to keep in mind the sequence "engage, activate, ntegrate".
5. Carefully Consider Your Musical Source
What's the best music to use for bilateral stimulation? The general idea, based on its origin in clinical use, is to use music that is not dramatic or even memorable. The music itself is the sonic platform the bilateral stimulation rides upon. Since EMDR and especially Brainspotting use acoustic bilateral stimulation to help the listener "go where they need to go" without outside influence, music in those situations needs to be neutral, just melodic enough to support a rhythm. A John Phillip Sousa march isn't going to cut it!
This doesn't mean the music can't be beautiful, for even in simplicity it is possible to convey a sense that "this is a sonic field capable of growing what you plant". For example, if you listen to "Discovered Underneath" which was composed by Lincoln Herring, for the first Alternating Sounds, LLC album from the first album "Written on Clouds: Bilateral Music for Healing and Growth", you'll notice that this simple melodic progression has a quiet gravitas, but does not overwhelm the bilateral qualities.
On the other hand, "IMAGO: a bilateral journey of transformation" is dramatic and propulsive from start to end. This is the reason it is NOT intended for clinical protocols (although it's very useful between sessions). Instead, both the music and the bilateral enhancements are intended to support ...... well, a bilateral journey of transformation.
The other major sonic platform for bls is the use of musically ambient drones, washes, pads, and so forth that have no melody but simply a present a light background without any tunefulness. Three examples from the album "From Old Illusions to New Conclusions that have no melody are "On Earth, Safe", "Strong and Noble Heart" and "Open Waters".
A different format entirely is "The Emptied Can" from the first album. The prime channel is a group of chanting monks, eventually supimposed by an acteual field sound of a can rolling across an open plain. I thought the imagery of an empty container fit with the idea of monks transcending their thoughts into a space of emptiness.
All this is to highlight various ways you can select your primary sound sources to suit your purpose.
6. Take Equal Care With Your Secondary/Tertiary Sound Sources
Now that we've reviewed the ideal elements of the primary sound source, it's time to turn to what constitutes the best second and third layers (assuming you are mixing multiple simultaneous bilateral stimulation levels, as noted above -- and why wouldn't you?)
One obvious rule is that your backup sounds need to be very subtle compared to your primary source. The point at this stage is mainly to give the listener multiple strength ranges for ideal neural engagement, and it doesn't take much to do this.
A classic secondary sound source, which is used in lots of meditation music, is some soothing environmental sound. I've effectively used gentle rain, ocean waves, gently lapping water, or a stream. None of these sounds dominate the listening experience, but all of them are soothing in themselves and can be bilaterally enhanced very easily.
By the way, one sound that seems like it would be useful but which is actually hard to convey in a recording is wind. The only way to "hear" wind is to listen to what it is moving, generally leaves or wind chimes. I tried t capture rustling leaves many times but it always came back sounding more like crumpling a paper bag of just being a generic "wash". However, I did successfully use the actual sound of wind against the tops of elm trees in one of the Scandinavian countries. (I have to admit I don't remember right off hand which selection in the catalogue uses this technique. I think it's "On Earth, Safe."
This is an appropriate place to direct attention to a wonderful source for environmental and other unique sounds is "Freesound", a site where people upload sounds they have created or captured. Most are available for sampling or other use, based on the degree they are copyrighted. I've harvested very many public domain sounds of all types: crowds, songbirds, city traffic, pasture animals with bells, etc.
One very different approach to using primary and secondary/tertiary sound sources is "Fertile Field: An Extended Bilateral Soundscape for Healing and Growth" which consists of a sound healer playing 7 crystal singing bowls for four minutes each, totaling an almost half an hour. Each singing bowl was said to correspond to each of the seven chakras or energy centers in the body. I very laborious created a soundscapes that moves from birds to growing rain, to a thunderstorm, to the slow ending of the rain and ending with crickets and croaking frogs. (In the process I learned that correct choice, placement and mixing of thunder is probably worth an article in itself!)
The final point in this section relates to the third sound source. Since this source is used to provide a "stabilizing" bls of no more than about 10%, it can be just about anything neutral. I successfully used song birds and streams although I try not to over-rely on those since they are pretty standard across all bilateral music.
Actually the last point about the stabilizing sound source is that it can just be a tone. Iv'e used carefully chosen frequencies and tones that 'fit' with the primary source. A very soft tone can usefully serve the purpose.
7. Look For, But Be Cautious About Cross-Panning Opportunities
Bilateral cross-panning is simply two sounds that are moving in opposite directions at the same time, crossing in the middle of the sonic field. My experience is that cross-panning can be overwhelming to an activated brain. I generally feel 'over-loaded' when I experiment with it.
So far the only successful example of cross-panning is the fourth movement of "IMAGO: a bilateral journey of transformation". Since this section represents a sky full of butterflies, the cross-panning quite effectively captures the fluttering patterns of their flight.
So if anyone reading this article comes up with an effective use of cross-panning, please elt me know!
8. Consider Your Ideal Track Length
Many bilateral recordings from the various companies that make them, including Alternating Sounds, LLC, are about the length of a regular piece of music, generally about four to six minutes.
For clinical purposes such as Brainspotting, however, I think longer is better. This is why three tracks from "From Old Illusions to New Conclusions" are over ten minutes long. Otherwise, a client in deep processing may be "jostled" a bit by the music changing ery few minutes. Since it is difficult to get a true melody to last that long, these long tracks all use ambient sounds that have no fixed length of time.
9. Consider The Careful Use of Binaural Beats
Binaural beats are the pulsations that occur when two tones are slightly apart. For example, playing two tones at 300Hz and 312Hz yields a pulse wave that occurs twelve times a second. There is some pretty widespread conventional wisdom, with some scientific support, that these waves are associated with different mental states based on their range, which are gamma (greater than 30Hz), beta (13 to 3Hz), alpha (8 to 12Hz), theta (4 to 8 Hz), and delta (less than 4 Hz).
To over-simplify this range, consider that the primary mental state ranges to consider for our purposes from alert (low beta to high alpha) alert to dreamlike (theta).
Here's the problem: since binaural beats are obtained by the conjunction of two tones, it's inevitable that one tone or the other will be very weak to occasionally non-existent in the case of 100% bls. One solutions I've used is to mimic this effect by 'pulsing' one tone the number of times per second to correspond to each wave range.
For example, several of the longer selections in the Alternating Sounds, LLC catalogue include extremely soft inclusion of beats that start about 12Hz and then very gently slow to about 4 Hz. One example that immediately comes to mind is "The Emptied Can" mentioned above.
The bottom line is that it is possible to incorporate binaural beats with bilateral stimulation. I'm personally not sure how much this helps the engagement/entrainment process, but it certainly doesn't seem to get in the way.
There's a little more information to share but this has been a lot so far, so check back to learn more "bilateral best practices" to keep in mind when creating your own music.
Comments and questions are always welcome.