For techies only.
A paper of the Central Institute for Labor Protection, Poland, (pdf) “Effects of Ultrasonic Noise on the Human Body – A Bibliographic Review”, is so highly relevant, an addendum is required. In Sonic Attacks on U.S. and Canadian Diplomats in Cuba; a Kremlin Op?, I wrote,
But there are ways, in theory if not practice, to project a concussive beam….Simultaneous hearing loss and concussive damage do not correspond well with a single attack frequency. Concussive damage without direct contact with the skull requires very high power.
A directed energy sonic weapon could take the form of a wave packet projector, an array of broadband piezo transducers working off lookup tables and adaptive algorithms. The report of concussion-type symptoms suggests a packet pulse rate at the resonance the cranial cavity.
The problem with the above is that because of impedance mismatch between air and human tissue, very little energy of the beam would enter the skull, not nearly enough to produce observable changes in brain tissue. But reminding us that symptoms, functional change, and pathology are not the same thing, the above paper provides a loophole. Quoting,
Workers using ultrasonic devices suffered from functional changes such as neurastenia, cardiac neurosis, hypotension, heart rhythm disturbances (bradycardia) and adrenergic system disturbances . Studies showed that exposure to sounds with a frequency of 21 kHz and level of 110 dB for 3 h daily for 10–15days caused functional changes in the cardiovascular and central nervous systems . Workers exposed to noise emitted by ultrasound devices suffered from increased neural excitability, irritation, memory problems and difficulties with concentration and learning . Roshchin and Dobroserdov indicated that lev-els of 90–110 dB within the range of lower frequencies (21kHz) and 110–115 dB within the range of higher frequencies (40kHz) constituted the limit of occurrence of functional changes .
This is an assertion that sonic devices of reasonable power can cause micro-structural changes in the brain, significant to neurological functioning, but with different pathology than normal concussion. This solves the major hurdle in explanation of the Havana events . Devices achieving these levels, either beam forming packet projector, or externally powered passive gadgets, are feasible.
And who are the authors of [35 and ? They happen to be Russian:
35. Il’nitskaia AV, Pal’tsev IuP. [Combined action of ultrasonics and noise of standard parameters]. Gig Sanit. 1973;(5):50–3. In Russian. 36. Roshchin AV, Dobroserdov VK. [Reactions of the human auditory analysor to the effect of high frequency acoustic oscillations]. Gig Tr Prof Zabol. 1971;15(12):3–7.