A declassified 2018 State Dept report suggests noises linked to ‘Havana Syndrome’ were probably just crickets

• An advisory group for the State Department analyzed sounds associated with the "Havana syndrome."
• The 2018 report, now declassified, found the sound was likely made by a particularly loud cricket.
• The report found that the sounds were not likely to have caused the potential medical effects.
• See more stories on Insider's business page.

A 2018 State Department inquiry into the loud noise associated with a mysterious set of symptoms nicknamed the "Havana Syndrome" found that the sound was probably caused by local crickets.

The document, which was originally marked as "secret" and has since been declassified, was obtained by BuzzFeed News using a freedom of information request.

The so-called Havana Syndrome is characterized by symptoms consistent with a head injury such as balance issues, visual impairment, tinnitus, trouble sleeping, headaches, and problems with thinking or remembering, Insider's Aylin Woodward previously reported.

Several who had symptoms consistent with the "syndrome" reported hearing a high-pitched noise, a recording of which was published by the Associated Press in 2017 and can be heard in the video below.

While the declassified report suggests a cause for the noise, it does not purport to explain the other troubling symptoms.

Despite increased attention in the years that followed, no conclusive explanation has emerged as of October 2021.

But the 2018 State Department report, led by the JASON, a group that provides scientific advice to the Pentagon on matters of national security, found that the "most likely source is the Indies short-tailed cricket," BuzzFeed reported.

These crickets, also called Anurogryllus celerinictus, are known to be particularly loud. Below is a recording of the crickets in Jamaica:

The findings are consistent with those of a study published in 2019.

It is still not clear what might be causing the putative syndrome.

Symptoms consistent with the unexplained set of symptoms, which gets its name from the first reported cases in Havana, Cuba, in 2016, have been reported for more than 130 spies, diplomats, military service members, and other US personnel so far, as well as two people close to the White House, according to reports.

A 2020 National Academies of Science found that the most plausible explanation for the symptoms appeared to be "pulsed radio frequency energy," although it could not rule out other leading theories such as chemical exposures, infection, or psychological issues.

Cheryl Rofer, a retired chemist from Los Alamos National Laboratory, previously told Insider that if a microwave weapon had been used, there would be physical marks of the attack.

"The evidence would be on the outside of their body," she told Insider's Aylin Woodward, adding: "It would be like a thermal burn."

The Pentagon has asked its 2.9 million service members to come forward if they have felt symptoms consistent with the "syndrome," according to a memo seen by The New York Times.