The Radio Science Bulletin No 374 (September 2020) 89 Telecommunications Health and Safety James C. Lin University of Illinois at Chicago 851 South Morgan Street, M/C 154 Chicago, IL 60607-7053 USA E-mail: lin@uic.edu Sonic Health Attacks on Havana- Based Diplomats Using Pulsed Microwaves A s I write this article, the US National Academies of Sciences, Engineering, and Medicine (NASEM) have just released their study report on “An Assessment of Illness in U.S. Government Employees and Their Families at Overseas Embassies” [1]. It has been about three years since the publication of my article describing the mystery of sonic health attacks on Havana-based diplomats [2]. It was first hypothesized in this paper, assuming that the reported events were reliable, that there was actually a scientific explanation for the source of sonic energy. It could well have been “from a targeted beam of high-power microwave pulse radiation.” In examining plausible causes of the described illnesses, the NASEM report [1] pronounced that among the mechanisms the study committee considered, “directed, pulsed radio frequency (microwave) energy appears to be the most plausible mechanism” in explaining these cases, especially in individuals with the distinct early symptoms. The hypothesis of a microwave auditory effect [2] was based on years of published laboratory and theoretical research. A minuscule but rapid (~μs) rise in tissue temperature (on the order of a micro degree), resulting from the absorption of pulsed microwave energy, creates a thermoelastic expansion of brain matter. This small theoretical temperature elevation is hardly detectable by any currently available temperature sensors, let alone felt as a thermal sensation or heat. Nevertheless, it can launch an acoustic wave of pressure that travels inside the head to the inner ear. There, it activates the hair-cell nerves in the cochlea, which then relay it to the central auditory system for perception, via the same process involved in normal sound hearing [3-6]. Depending on the power of the impinging microwave pulses, the level of induced sound pressure could be considerably above the threshold of auditory perception at the cochlea: approaching or exceeding levels of discomfort (including the reported headaches, ringing in the ears, nausea, and problems with balance or vertigo), and even causing potential brain-tissue injury. It is important to note that in recent clinical radiological examinations, compared to individuals not experiencing the loud bursts of sound, brain magnetic resonance imaging (MRI) revealed significant differences in whole-brain white- matter volume, regional gray- and white-matter volumes, cerebellar tissue microstructural integrity, and functional connectivity in the auditory and visuospatial subnetworks, but not in the executive control subnetwork [7]. However, the clinical importance of these differences is not definitive. Nevertheless, a high-power microwave-pulse-generated acoustic pressure wave can be initiated in the brain and then reverberate inside the head, and potentially reinforce the initial pressure to cause injury of brain matters [6]. While the clinical symptoms presented are concussion- like, the MRI images did not resemble usual presentations of traumatic brain injury or concussion. However, clinical experiences with concussion are mostly derived from externally inflicted impact injuries, such as a hit to the head against the ground or other rigid bodies, which may set brain tissues into violent motion against the skull. A high-