We’re not actually going to. This will be informed speculation, guided by open source physics and electronics. But perhaps it will inspire some young budding Dr. Evil to a lifetime of work. It all depends on your idea of fun.

Let’s consider the general shape of the package:

• Futuristic. Eventually, all surfaces will be active. The attack vehicle  could be the wall paper itself, containing printed circuits and patches of active material that transform electricity into sound. With the huge area provided by wallpaper, it is actually possible to contemplate powering it by radio waves. The time is not yet.
• Practical. It could be something quite prosaic, hidden in a hot water heater. Metal pipes are efficient conductors of ultrasound. It could be powered without easily detectable connections. By disconnecting some of the plumbing from “ground”, the pipes themselves could carry a low voltage, high amperage supply. I am confident this has been done one time or another.
• Sound cannon. The use of sound as a projectile has attracted interest since about 1900.  But why would sound work at all? Sound carries energy. All weapons other than CBW work by transferring energy to the target in a way to make it stop working.

We will focus on the sound cannon. The portable nature of this hypothetical device, and the multiple locations of the attacks, conform with the inability of the F.B.I. to locate the source.

How much energy is required? It turns out that it’s not the amount of energy that counts, but how it is delivered. If you walk down a flight of stairs, your foot pads absorb the slight shock of each step. But if you fall down, you hurt yourself. The effect increases rapidly with height. Two flights is nothing for your feet. Try jumping off the roof and let me know. A pistol bullet has less energy than a medium firecracker. So the delivery is more important than the total.

Nuclear radiation provides another insight. The total energy in a lethal whole-body dose of gamma-rays is less than the energy in a cup of coffee. But it is delivered in a range of frequencies called the “ionizing band”, which knock electrons loose from atoms. The victim feels nothing, yet it kills.

One form of air disturbance, the pressure pulse of a bomb blast, lethally ruptures the lungs. But inconveniently for the designer, it takes a lot of energy to create the pulse. Our designer would like a solution that uses minimal energy to fry a brain. The press has recently served up a bunch of experts who assert this is impractical. Havana Sonic Attacks — Addendum for techies only, refers to Russian references in a Polish paper, “Effects of Ultrasonic Noise on the Human Body – A Bibliographic Review”, which imply it is eminently practical.

The Russian references indicate that the unintended spillover of industrial devices such as ultrasonic welders can, with prolonged exposure, cause the effects reported to afflict the Havana diplomats. The first thought of an engineer is, if this is accidental, can one do “better” by design?  “Better” is quoted because many engineers would not consider this fulfilling work. It strikes me as something that would take as cold a heart as Dr. Evil, or Gordon Gekko in Wall Street,  to pursue without internal conflict.

So let’s be Dr. Evil for this article. The object is to scramble the brains of John Doe with a compact, practical, portable device. This implies a ultrasonic beam, that can project to a target some moderate distance away. With sound, distances are meters, not miles.

Through tragic lack of imagination, the “experts” cited by the press (hopelessly naive CNN video)  are stuck with the most prosaic of assumptions:

• The beam has a single frequency.
• The energy is delivered continuously.
• The device is big and bulky.

Their thinking is stuck in a tiny box. Let’s think outside the box:

• The beam can be composed of a complex combination of multiple frequencies with multiple effects and enhancements. A complex, time-varying waveform.
• The intensity can change rapidly, for specific purposes and optimizations: penetration, resonance, efficiency.
• Since the device does not deliver continuous power, it can be small and compact.

Since the device must deliver a complex waveform, forget about the “experts” who say this gadget can be built by anyone with modest engineering talent with off-the-shelf parts. It cannot. Your first stop will be to the funding office. Ask for $50M.  You’ll need at least one specialist in each of these:

• Physics,  hydrodynamics of compressible fluids.
• Ultrasonic transducers, experience in both piezoelectric and magnetostrictive types.
• Antenna theory, someone who transferred into ultrasonics.
• State-of-the-art ceramics fabrication. This is not pottery at the neighborhood art center.
• Control theory and heuristics.
• Electrical engineering,  Class-D amplifiers.
• Electrical engineering, power supplies.
• Software engineering, real time and wave tables.
• Software engineering, user interface.

This is a lot of work, but in the end, you’ll have the satisfaction of pointing it at a CNN “expert” and asking, “How much do you want to bet this doesn’t work?” If you interest flags, remember, glory awaits the next Dr. Evil.

To be continued shortly.