That’s the hypothesis put forward by two researchers from the United States and England in a paper published last week that studied the sound waves produced by a mysterious recording of a high-pitched buzzing noise that officials have said is linked to illnesses that have stumped investigators for more than a year.
“The sounds recorded by U.S. personnel in Cuba correspond to the calling song of a specific cricket, with echoes.”
WATCH BELOW: State Dept. not assigning blame for U.S. diplomats’ illness in Cuba
Between November 2016 and April 2017, American diplomats posted in Cuba began reporting symptoms including headaches, nausea, memory issues and other problems, prompting American officials to ask Canadians if they were receiving similar reports.
In August 2017, five Canadians and 16 American diplomatic staff were confirmed to be suffering symptoms.
Some — but not all — also reported hearing an unidentifiable buzzing noise around the same time.
By January 2018, the number of affected Canadians increased to eight, then to 10 in April 2018, then 13 in November 2018.
As of September 2018, 26 Americans were affected.
In late 2017, American officials yanked roughly 60 per cent of their diplomat staff out of Cuba as the mystery continued.
They also released an audio recording to the Associated Press that officials suggested could be linked to the incidents.
WATCH BELOW: Canada has no clue what made Cuba diplomats sick
That recording prompted speculation that the concussion-like symptoms reported by diplomatic staff could be the result of what was dubbed a “sonic attack” using an unknown device or weapon, despite the fact that not all those who reported symptoms said they heard the noise.
Potential possibilities floated included malfunctioning eavesdropping equipment or the byproduct of some kind of weapon using microwave beams.
A joint investigation involving both Canadian and American authorities remains ongoing but has not yet resulted in a public explanation.
One report by NBC News last year cited intelligence sources as saying the investigation was focusing on Russia as a main suspect as a result of intercepted communications.
The Cuban government had initially suggested the recording was of a Jamaican field cricket but the researchers noted they are not surprised American officials dismissed that possibility early on because that species of cricket produces a very different kind of sound than the one they suggest could be behind the recording in their new paper.
Specifically, the researchers suggest an echoing cry of the Indies short-tailed cricket, such as one heard from within a space with tile floors and drywall, is responsible for the noise.
But while they argue the sound itself can be explained, the symptoms reported by diplomats remain unexplained.
“Thus, while disconcerting, the mysterious sounds in Cuba are not physically dangerous and do not constitute a sonic attack,” the researchers stated.
“The fact that the sound on the recording was produced by a Caribbean cricket does not rule out the possibility that embassy personnel were victims of another form of attack. While the causes of any signs and symptoms affecting U.S. personnel in Cuba are beyond the scope of this paper, a biological origin of the recorded sounds motivates a rigorous examination of other possible origins, including psychogenic, of reported neurophysiological effects.”
WATCH BELOW: Canada pulls families of diplomatic staff from Cuba after mysterious health symptoms
Documents obtained by Global News last year under access to information laws showed Canadian officials initially wondered if the symptoms were all in diplomats’ heads or whether they could be explained by extreme stress or fear of being targeted.
The disclosed emails, spanning from April 2017 to August 2017, were marked “secret” and the vast majority were stamped “for Canadian eyes only.”
“Whatever we are dealing with, HAVAN [the Havana embassy] is clearly seriously concerned and employees’ well-being is being affected. It could well be that only testing will relieve their concern,” reads a May 16 email sent between senior Global Affairs Canada staff, that discusses how to deal with the unclear situation and whether to ask for medical testing.
“Many of the symptoms are similar to signs of extreme stress, and there is the possibility that there could be mental health effects caused by the fear of being targeted. Either way, testing should help to rule out cases and reassure personnel that we have the means to be able to provide duty of care.”
By April 2018, however, Global Affairs Canada has upped the risk rating for the embassy in Cuba to the same level as the one in Afghanistan.
Officials also changed the classification of the posting to prevent diplomats who agree to go there from bringing their family with them.