14ymedio, Havana, January 8, 2019 — The audio disseminated in October of 2017 by the Associated Press agency which supposedly reproduces the strange sound heard by the staff of the American embassy and which presumably caused brain damages in almost forty officials of Washington and Ottawa, matches the calling song of the short-tailed cricket, according to a study published by scientists from the University of California at Berkeley. The official press didn’t take long to echo the news and published the results of the study on Saturday.
The study, which is not intended to settle the damages caused nor the supposed attack, focuses on analyzing the sound, and determines that there are up to six lines of evidence that it is the noise produced by this insect typical of the Caribbean and common on the Island, whose scientific name is Anurogryllus celerinictus.
The academics Alexander L. Stubbs and Fernando Montealegre, from the Biology Department and the Museum of Vertebrate Zoology of the California university, say that “the calling song of the Indies short-tailed cricket of the Caribbean matches, in nuanced detail, the AP recording (…)” in terms of “duration, pulse repetition rate, power spectrum, pulse rate stability, and oscillations per pulse.”
The study’s conclusions may call into question the origin of the audio or its possible relation with the injuries caused to the diplomats, although they do not question whether these occurred.
“This provides strong evidence that an echoing cricket call, rather than a sonic attack or other technological device, is responsible for the sound in the released recording. Although the causes of the health problems reported by embassy personnel are beyond the scope of this paper, our findings highlight the need for more rigorous research into the source of these ailments, including the potential psychogenic effects, as well as possible physiological explanations unrelated to sonic attacks,” maintains the study.
“The line of evidence supports the conclusion that the sound recorded by US personnel in Cuba is of a biological origin and does not constitute a sonic attack. The fact that the sound in the recording was produced by a cricket does not rule out the theory that Embassy personnel were victims of another type of attack,” adds the document.
The mystery of the sonic attacks, as the US refers to them, thus continues without being solved. American authorities maintain that at least 24 members of their staff stationed in Havana suffered migraines, nausea, and brain damage between the end of 2016 and August of 2016, which were, in their view, caused by advanced acoustic devices.
One of the most recent and elaborate scientific theories published was that provided in March 2018 by Kevin Fu, an expert in computer science at the University of Michigan, according to which the health problems of the officials had no relation with exposure to an acoustic attack, but rather with interferences caused by electronic devices.
Fu, in collaboration with professor Wenyuan Xu and his doctoral student Chen Yan at the University of Zhejiang (China), provided this theory based precisely on the audio of the Associate Press.
The frequency of that sound reached 7 kilohertz (kHz), far from the range of between 20 and 200 kHz typical of ultrasound frequencies, which are inaudible and which at an early stage were believed to be the causes of the intriguing event.
Through a series of simulations Yan showed that an effect known as intermodulation distortion could have caused the sound that was heard on the recording and that the Berkeley scientists now categorically affirm is crickets.
Intermodulation distortion is a phenomenon that occurs when two signals of different frequencies combine to produce synthetic signals.
Chen used two ultrasound speakers: one of 25 kHz and the other of 32 kHz. When he crossed the signals of both devices it produced a sharp sound of 7 kHz, which matched the difference in frequency between the two devices and which was the same that was heard in the AP audio.
“If ultrasound is the culprit, then a possible cause is two signals that accidentally interfere with each other, creating an audible secondary effect. Maybe there is an ultrasound blocker in the room and an ultrasonic transmitter,” suggested Fu in an alternative that led to the consideration that the devices that reacted to each other were microphones.
ProPublica had affirmed in February of 2018 that all the hypotheses dealt with until that point were ruled out except for the Russian clue. The digital outlet gave a detailed account of the events after listening to the testimony of various American officials. At the time the sound was heard, the possibility was mentioned that it might have an animal origin, but those affected were divided on the matter.
“I’m very sure that they’re cicadas,” said one of the officials. “They’re not cicadas,” responded another. “Cicadas don’t sound like that. The sound is too mechanical.”
The sounds were described as sharp and disorienting and the diplomats thought, initially, that they were usual episodes of surveillance or harassment that their compatriots have denounced since the United States Interests Section opened in 1977.
What appears beyond all doubt is that there are dozens of diplomats affected by a cause yet uknown but that the United States attributes to a sonic attack.
The options most used in cases of this origin are ultrasonic weapons, those of ultrasound and microwaves, although the first have been imposed because of their matching the symptoms described by the victims.
Translated by: Sheilagh Carey
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