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Infrasound generator specifications.  How to build a tuned, high-output infrasound generator.

             Building a powerful infrasound emitter is neither difficult nor terribly costly, once you understand the limitations of available technology.  Infrasonic output equivalent to a 2000 watt dynamic speaker can be accomplished with simple leaf blowers.  The problem, is one of defining the problem.  The solution then becomes obvious:


              Building a high-powered infrasound source of practical dimensions using dynamic speaker technology is a pragmatic impossibility, for two reasons:  a) the physical size of the device, and the mass of the moving components, increases dramatically as the design response frequency is decreased, and   b) the conversion efficiency of the dynamic speaker, which is unimpressive in any range, drops well below 1%.  What this means is that a 100-watt dynamic speaker, at full power, yields an output in the range of 0.5 to 0.9 acoustic watt.  Still, if you stand in front of a fully-driven 100 watt speaker outputting at, say, 100 hertz, you will gain an appreciation for the effect of even that level of acoustic power.  Now imagine that effect multiplied by 10.  Or 100...

            One obvious solution is to employ instead a tuned, single-frequency device which relies upon a different principle of operation—one which requires no moving parts:  a supersized whistle.  There are several whistle configurations, most of which have been tried and proven unsuitable for high-output operation:  (1)Flutes, which are either open-end or closed-end whistles, and  (2) the Helmholtz resonator, which is essentially an open vessel (a wine bottle, for example) with a constricted neck opening.  Blow across the neck opening and you get a low-frequency output.  As you drink more of the wine, thereby lowering the fluid level and increasing the air volume, the frequency gets lower as you get higher.  It’s a relationship long known to aspiring musicians: The more you drink, the better you sound.

            The disadvantage of the first two, of the flute variety, is well-known:  Overdrive either (blow too hard) and the resultant output degrades  into higher harmonics.  They squeal.  In addition, the size of the device is an inverse function of the frequency:  The lower the frequency, the larger the device.  A weapons scientist named Vladimir Gavreau ran into this problem while experimenting with infrasound in the 1960’s.  A half-wave, or open-ended flute, tuned in the neighborhood of 7 hertz, is several feet in diameter and 80 feet long.  Not exactly portable, to say nothing of the air supply required.  A quarter-wave, or closed-end device, is little better in this regard.

            The Helmholtz resonator was the earliest form of the fog horn.  The device was relatively small and compact, but output is limited for the same reason as in the flute:  Blown too hard, it produces higher-octave harmonics of the tune frequency. It too, squeals.


            There is a fourth type of air-actuated generator, which is essentially a vortex chamber with a circumferential emitter port.  Its operational threshold is high, meaning that its output is high within its very specific tuned range; it is of compact design; and it operates by design at a single frequency.  The principal of operation is as simple as the mathematics are complex, but one does not require a deep understanding of either in order to design and build such a device with off-the-shelf components  (A small version was powered by leaf blowers, simply to prove its feasibility as a back-yard project).  A few simple formulae are required to determine the precise design parameters for the desired frequency.  Before you flee in panic, there is no mathematical wizardry required which is beyond the scope of eighth-grade math.  If you can use a ten-dollar scientific calculator you can plug in the values you want, crunch the numbers and get your results.  As to the construction of the device itself, if you  can read a tape measure and use a power saw without dire risk to cherished body parts, building the emitter source is within your capabilities.      

            Two variations of this design are presented in the design/construction data, which I have made available below in CD form.  The first is a relatively low-powered version which is less than a cubic foot in size, and which is capable of output as low as the 15-30 acoustic watt range:  Suitable for delving into meditation or  ‘paranormal’ research, and competing with, or even upstaging, ‘boom cars’, in a moderately larger output configuration.  The second variation occupies as much as a cubic meter of space, is capable of output in the 200+ acoustic watt range—equivalent to the output of a 20,000+ watt dynamic speaker array—and has a theoretical effective range measured in miles.

            It should be noted here that the output from a vortex chamber is non-directional; it cannot be aimed, diverted, funneled or focused, so the detectable range is essentially the radius of a circle with the device at its center.  In some cases, this could be a very large circle.


             From deep, sonorous Gregorian chants to the Australian didgeridoo, low bass and infrasound has throughout time been associated with the quest for satori, or spiritual enlightenment. While results of the few studies into its efficacy in that regard have been contradictory and inconclusive,  the deep and continuous murmuring of a multitude of voices in tune does in fact induce a perceivable vibration within the human body; one which practitioners insist opens the way to a higher consciousness.  And anyone who has immersed himself for a time in such a ‘sound bath’  will readily admit that something is happening.

            The concept of binaural perception attempts to recreate this vibratory phenomenon within the brain alone, with mixed results.  The idea is to play two tones of differing frequencies, one into each ear (ideally through headphones), thereby creating a lower, differential ‘beat’ frequency which is perceived within the brain.  The best software we have found for generating these binaurals is offered by www.bwgen.com (The program is also extremely useful in fine-tuning the vortex chamber by beat frequency comparison—explained in detail on the CD).  Whether the brain will consistently ‘entrain’, or lock onto this differential frequency to attain alpha or other states, is a matter of some conjecture.  In any event the power level is extremely low and any such effect is perceived entirely within the brain, unlike the whole-body perception of infrasound-induced pulsations.

            If the binaural concept is extended to infrasound the result is markedly different.  Sitting near two infrasound emitters, each generating, say, 10-30acoustic watts, produces a beat-frequency, pulsating effect within the body which is undeniable.  Speaking only from our own anecdotal experiences, the effect varies from remarkable to—unsettling, depending upon the differential frequency chosen.

            As an example, the infrasound frequency of 18.98 hertz is the resonant frequency of the human eyeball.  A low-power output at this frequency has been shown to cause oscillations of the eyes which create the perception of ‘ghosts’ about the perimeters of vision:  you perceive fleeting, indistinct images.  This is a phenomenon which, to my knowledge,  has never been replicated with binaural headphones.            


              Infrasound in the range below 20 hertz cannot be heard; it can only be perceived as a bodily sensation.  The body as a whole being a much less sensitive receiver than the ears, the power level required for such perception is notably higher.  While the lower part of this region, in the range of 4-8 hertz, can serve to initiate alpha, theta or even delta states at perceivable power levels,  exposure to extremely high power levels within the same range, especially around 7-7.38 hz, may approach or induce resonance within the body cavity, with potentially serious side effects.  While the jury is still out with regard to the nature, intensity and range of those side effects,  deep infrasound remains very much dark territory.   Possibly for this reason, available information regarding practical means for generating powerful infrasound has been vague and generally misleading.  If, however,  one chooses to dabble in this region a modicum of caution is prudent; while the lower end of the power curve is home to many interesting and even beneficial phenomena such as in meditation, behavior modification and even healing (some veterinarians use a form of it),  the  high end may be the doorway to darkness; approach it with caution.  Here’s why:

             Regarding sound isolation, a rule of thumb is that the thickness of an isolating panel should be more than ¼ the wavelength of the frequency to be damped.  At very low frequencies this can be 40 feet or more of thickness.  While  the acoustic principle known as Mass Law has some effect here (lead shot and moist loam make good insulators), the sheer size of the required mass nevertheless becomes problematic.  Add to this the following characteristics of infrasound: 1) It follows positive temperature gradients—it hugs the ground, following the contour of the land;  2) Its attenuation rate is very low, meaning it retains power over distance;  3) Low-density masses, such as buildings, can become resonant.  While mid- to high-frequency emissions (1000 hz and higher) can be rather easily attenuated merely by placing a properly designed panel between source and receiver, infrasound will simply flow around (and through) it, with no discernible loss of power.  From a theoretical standpoint, the only real protection from infrasound is to be  found within a physically isolated sphere suspended, magnetically or otherwise, in a vacuum. 

            If this sounds like a pragmatic impossibility,  I congratulate you;  you’re alert, knowledgeable and reasonably sane.  The other option is to be out of range when, and if, you power up a high-output device.  This justified the remote vehicle experiments carried out by Mssr. Gavreau who also, incidentally, stumbled upon the vortex chamber as the obvious solution to the size conundrum.  However, the only printed information I have found regarding the tuning of this device appears to be no more than idle, and misleading, speculation.  I have therefore, after due consideration, decided to offer my findings on vortex chambers,  with the following caution:

             While high-energy research in this area is feasible on a shoe-string budget,  it is a field probably best left to those with more complete facilities than can be found in the average suburban garage.  Unless, of course, you aspire to honorable mention in the Darwin Awards.  The lower-energy devices offer more than enough range in power to experiment, seek satori or annoy the neighbors with your own version of the Taos Hum. 

            The information offered below is of an esoteric nature which, I believe, will be of interest to a limited audience:  those of curious bent, with the capabilities necessary to put theory into practice.  People with enough maturity and common sense to recognize and observe the limits of safety when dealing with a relatively unknown quantity.  It is offered in that vein, and with that caveat.  Nor can I guarantee that the user’s results will duplicate my own, since I cannot know whether the user is a detail-oriented innovator—or a bubba with a ball-peen hammer.  The tuning and construction details, while ample for the former, will be beyond the latter—as they should be.  Some people, after all, shouldn’t drive anything that doesn’t have pedals.  This information describes devices which operate on an event horizon, and training wheels are not included.

 ORDERING:   Why the  ‘Old Fashioned’ way?

 I am an industrial engineering consultant, not an Internet Entrepreneur;  I have therefore made no accommodation for credit transactions.  If you want the CD bearing my equations and drawings, payment is accepted in the form of certified bank draft or money order, payable in U.S. currency.  The cost, shipped via U.S. First-class Mail,  is:

 ·        In the USA :  $ 35.00 (includes shipping/handling)

·        Anywhere else:  $ 38.00

 Made Payable to:

                                    James K. Smith
                                    P.O. Box 119
                                    Flora Vista, New Mexico, USA - 87415

                                    Questions? kgcoyote@yahoo.com

Infrasound Designs: Generator Specifications