This article sketches another design for an ultrasound weapon.

CNN: Study: US personnel suffered ‘symptoms resembling brain injury’ in Cuba. Quoting,

The report found “audible or sensory phenomena” were from an unknown source but came from a specified direction. In conclusion, the authors say their study raises “concern about a new mechanism for possible acquired brain injury from an exposure of unknown origin.”

I’ve written extensively about this. You could start with Senate Hearings on Havana Sonic “Attacks”. Further articles are accessible through this link. Quoting further,

“We actually don’t think it was the audible sound that was the problem,” said Dr. Douglas Smith, another of the study’s authors….We think the audible sound was a consequence of the exposure,” added Smith, who is the director of the University of Pennsylvania’s Center for Brain Injury and Repair.”

That’s right. The audible component was not responsible. It’s just a byproduct of nonlinear mixing of ultrasonic components.

In order to overcome skepticism of a practical ultrasound weapon, I wrote a six-part series on the design of such a weapon, beginning with  Havana Sonic Attack Weapon — Let’s Build It! Part 1.  Although I attempted to anticipate Russian capabilities, my design does not necessarily resemble the actual weapon. There are probably six ways from Sunday to design one. My design is a didactic example, separating  the problem into easily digestible pieces.

Fragments of the victims’ experience suggest possible deployment of more than one design. Quoting, “One patient said they heard two short 10-second pulses,…” , differing in duration from all the other reports. Was this divergence the result of:

• Immediate dysfunction of the auditory nerve?
•  Efficient, active nulling of the audible mixing product by the weapon?
• Delivery of tremendous power in a short interval, differing with the long duration of exposure of the other patients, requiring less power?

Given Russia’s relative strength in hydrodynamics and weakness in electronics, a Russian design might be even less electronic and more mechanical. So here’s another design. Unlike  the “Let’s Build It” series, it isn’t going to help the typical reader of this blog understand what is going on. But physicists will understand immediately:

• The ultrasound generators are arrayed around a cavity filled with gas under high pressure. The pressure increases the “characteristic impedance” of the gas, so the generators can couple better.
• The gas could be a non-ideal gas-law “gas”. Instead of PV=NRT, it has a triple point near room temperature. A Freon, perhaps.
• Multiple coupled cavities can be used for impedance matching.
• The frequencies of the sound generators are adjusted to random correlation, so the mixing products are “white”. This doesn’t help with power, but the combination still contains peaks.  Goal: sigma that exceeds Gaussian.
• My first design used piezo transducers to generate ultrasound. The actual weapon may use ultrasonic gas whistles, or cavitation coupled to resonance. For high power, the gas whistle could be powered  by deflagration, or detonation slowed to subsonic by a “gas capacitor.” For longer duration with less peak power, gas could be pumped or stored in an accumulator.

The above design is not a good explainer, but it fits well with Russian capabilities. It could have been built by the 1950’s.