ABOVE: US embassy in Havana, Cuba

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A recording of a high-pitched sound thought to be connected to a possible “sonic attack” on diplomats in Cuba is actually the calls of a cricket, scientists who analyzed the tape reported last week (January 4) at the annual meeting of the Society of Integrative and Comparative Biology in Tampa, Florida.

“There’s plenty of debate in the medical community over what, if any, physical damage there is to these individuals,” Alexander Stubbs of the University of California, Berkeley, tells The New York Times. “All I can say fairly definitively is that the A.P.-released recording is of a cricket, and we think we know what species it is.”

The Associated Press (AP) distributed the recording of the sound in October 2017. The news outlet did not disclose where it had received the tape, which it noted at the time “sounds sort of like a mass of crickets.” During that year and the one prior, US diplomats in Cuba had complained of headaches, nausea, dizziness, and other symptoms. Some also reported hearing a piercing noise—the one caught on tape.

Doctors found that the diplomats had suffered brain injuries. For instance, in JAMA last year, physicians concluded that the patients they examined “sustained injury to widespread brain networks without an associated history of head trauma,” and that all had been exposed to unidentified “audible and sensory phenomena.”

For Fernando Montealegre-Zapata, a professor of sensory biology at the University of Lincoln in the UK, the sound reminded him of the crickets he collected as a child, according to The Guardian. So he and Stubbs searched a database of insect sounds to see if any matched the tape from the AP.

The Indies short-tailed cricket, Anurogryllus celerinictus, was close, but not a perfect fit. Perhaps, they reasoned, it was because the Cuban tape was made indoors, while the recording in the database came from outdoors. When the scientists played the cricket call from the database in a room to capture possible echoes that might have occurred when the Cuban sound was taped, the sound features were more aligned with those of the “sonic attack” recording.

“The paper shows how the cricket’s song could, when echoes to be expected in an indoor setting are taken into account, produce sounds strikingly, and quantitatively, similar to that provided by the AP,” Gerald Pollack, who studies sensory biology at McGill University in Montreal, tells The Guardian. “I find this a completely plausible explanation.”

Douglas Smith, a coauthor of the JAMA study who studies neurotrauma at the Perelman School of Medicine at the University of Pennsylvania, tells the Times that patients heard a range of sounds, and some none at all. “These patients have gone through a lot,” he says. “I would like to know what the sounds are, but for us the more important thing is really what’s going on in the patients’ brains and what we can do about it.”