A theory that the cause of "a mysterious acoustic attack to the American Embassy in Cuba" is in "interference of ultrasound" appears

ByJason Corey

A case in which an employee of the American Embassy in Cuba complained of health hazard due to a mysterious high frequency was reported that there is a possibility of a new sonic weapon in part. However, research by researchers in the United States and China pointed out the possibility of being an unexpected accident caused by interference between ultrasonic waves.

On Cuba, Diplomats, Ultrasound, and Intermodulation Distortion
(PDF file)https://spqr.eecs.umich.edu/papers/YanFuXu-Cuba-CSE-TR-001-18.pdf

Finally, a Likely Explanation for the "Sonic Weapon" Used at the U.S. Embassy in Cuba - IEEE Spectrum
https://spectrum.ieee.org/semiconductors/devices/finally-a-likely-explanation-for-the-sonic-weapon-used-at-the-us-embassy-in-cuba

Between December 2016 and August 2017, an incident occurred in which the staff of the American Embassy in Cuba continued to be exposed to high-frequency sounds and the health was harmed. For a series of cases that became a major problem, such as the possibility of 'unknown acoustic attack' aimed at government agencies in the United States is pointed out, it can be confirmed in the following article.

What was going on at the American Embassy in Cuba where "acoustic attack" was reported? - GIGAZINE


Partial noise of 'Acoustic Attack', Fear of damage caused by hearing loss or brain damage - GIGAZINE


Various analyzes were carried out when the high frequency data recorded by AP communication was released, and analysis result that "sound wave weapon by high frequency was used" was given, acoustic experts said " The possibility is low ". According to experts in acoustics, ultrasonic waves of 20 - 200 KHz do not spread well in the air, they do not cause symptoms such as tympanic pain, headache, dizziness, and ultrasonic waves can not be heard by the human ear Despite the victims there are people who are listening to treble.

Dr. Kevin Hu, a computer scientist at the University of Michigan, analyzed the voice data of "mysterious acoustics" recorded in June 2017 and noticed that there was an abnormal ripple in the spectrum plot. Dr. Fu, a researcher who specializes in analyzing cyber security such as pacemakers, RFIDs, automatic driving vehicles, IoT terminals, and the like, Cuba's mysterious sound has a certain "interference" from the spectrum ripple It seemed like it seems.

In search of cooperation from Dr. Shu Wenyang of Zhejiang University in China who is researching and developing speech recognition system and automatic driving car, Dr. Fu investigated sound interference. They analyzed the exact frequency and amplitude of the signal by fast Fourier transforming the recorded speech data. About this analysis, Dr. Shu felt "It is an interesting" puzzle. "Solving the puzzle was fun."


As a result of performing various simulations, the two were "Mutual modulation distortion"We discovered that the problem sound could have occurred by a phenomenon called" The intermodulation distortion is a phenomenon that when two signals having different frequencies are combined, the difference or sum of the original frequencies and a new composite signal is generated by the multiples. Dr. Fu says "Intermodulation distortion may generate a signal with a lower frequency than the original signal, in other words, ultrasonic sounds that are not heard in the earlier stage combine to create a" byproduct "that can be heard by the ear It is possible to have it. "

Dr. Yang who continued his research succeeded in generating high frequency sound of 7 KHz which is the same as the recorded mysterious sound by using ultrasonic sound which can not be heard by human ear both 25 KHz and 32 KHz. In the following movies, we successfully played "Never Gonna Give You Up" embedded as ultrasound by making two ultrasounds interfere.

Covertly Exfiltrating a Song with an Ultrasonic Carrier - YouTube


Dr. Fu who succeeded in reverse engineering the mysterious sound that hit the American embassy in Cuba examined what kind of signal combination caused mysterious sound. As a result, because there are some staff listening to audible sounds, we point out the possibility that ultrasonic jammer and ultrasonic transmitter were in the room. In addition, Dr. Fu thinks that there is a possibility that the person installing each terminal may be different, in that case, you may not have noticed that trouble may occur due to interference with other terminals.

Dr. Fu's paper "Reverse Engineering the 'Sonic Weapon.'" That the mysterious sound that hit the American embassy in Cuba is possibly generated by interference between ultrasonic waves is in March, 2018 It is scheduled to be published in.