The suggestion that sonic attacks caused brain injuries among U.S. diplomats and others in Havana was “speculative and premature,” according to an Oct. 31 article in the Journal of the Acoustical Society of America.
“The evidence to date points away from these conclusions,” wrote Timothy G. Leighton, a professor of ultrasonics and underwater acoustics at the University of Southampton in England.
A powerful driver to the momentum these “ultrasonic death ray” stories have had since their inception in the 1950s has been the impression that the exposures are covert.
Fear of a covert acoustic attack can lead to anxiety and other symptoms that mirror symptoms resulting from an actual attack, Leighton wrote.
This foreseeable result should have been balanced against the paucity of data linking acoustic conditions in Cuba to the reported symptoms.
Public exposure to ultrasound, poisoning, pathogens and drugs can also cause similar symptoms. Leighon wrote:
Currently everything in the evidence points away from labelling the events in Cuba and China as being ultrasonic attacks that caused brain injury. These terms are emotive and misleading. First, the only evidence that this is sonic, let alone ultrasonic, is indirect testimonies that have not been published, and as someone who deals with anecdotal reports of ultrasonic attacks, there needs to be much greater weight of evidence before this is termed “sonic.” Second, as someone who has investigated many purported claims of ultrasonic attacks, I have never found one to be an actual attack. They were either not acoustic, or if they were, were accidental exposures. Third, references to brain injury caused by such an attack do not reflect the evidence in the scientific and medical tests that were conducted on the people who were examined.
They Havana incidents may have been unintentional, according to a March 1 manuscript called “On Cuba, Diplomats, Ultrasound, and Intermodulation Distortion.”
In the paper, Chen Yan, Kevin Fu, and Wenyuan Xu wrote:
While our experiments do not eliminate the possibility of malicious intent to harm diplomats, our experiments do show that whoever caused the sensations may have had no intent for harm. The emitter source remains an open question, but could range from covert ultrasonic exfiltration of modulated data to ultrasonic jammers of eavesdropping devices or perhaps just ultrasonic pest repellents. It’s also possible that someone was trying to covertly deliver data into a localized space using ultrasound to say, activate a sensor or other hidden device.
Our experiments (see details) show that tones modulated on an ultrasonic carrier by one or more parties could have collided invisibly to produce audible byproducts. These audible byproducts can exist at frequencies known to cause annoyance and pain. Other theories include solid vibration (e.g., unwittingly standing on a covert transmitter) at ultrasonic frequencies for prolonged periods—leading to bodily harm.