On an evening in November 2016, a U.S. diplomat stationed in Havana, Cuba, opened the doors from his living room into his garden, and noticed a loud, high-pitched sound. As he later explained in an interview with journalism organization ProPublica, the noise was so intense that the only way to block it out was to close all the doors and windows and to turn on a television. Other diplomatic personnel began to notice the sound as well. One thought it was made by cicadas, but another described it as sounding too mechanical to be an insect.
But suspicions soon arose that the sound was more than just a peculiar annoyance. In the months that followed, dozens of U.S. diplomatic staffers — as well as some Canadian personnel — began to suffer from a series of health problems, ranging from headaches, sleep disturbances and memory problems, to hearing loss and difficulties with balance. Eighty staffers and family members returned to the U.S. for medical examinations, and 21 of them were evaluated further by the University of Pennsylvania's Center for Brain Injury and Repair.
As State Department official Todd J. Brown testified in a Jan. 9, 2018, Senate hearing, U.S. officials in Havana and Washington suspected that the diplomatic staffers' injuries had been caused by a deliberate attack, intended to harass them, and the FBI eventually was called in to investigate. Accusations arose in the news media that some sort of mysterious sonic weapon had been used, and in October 2017, the U.S. ordered 15 Cuban diplomats to leave the country for what it said was Cuba's failure to protect the Americans from whatever had caused their injuries. The Cuban government denied responsibility, and the country's own experts hypothesized that stress over U.S.-Cuba relations might have triggered the diplomats' health problems.
This recording of the noise later was obtained by the Associated Press:
What happened in Havana, unfortunately, remains a mystery. In an article published Feb. 15, 2018, in the Journal of the American Medical Association (JAMA), the Penn doctors concluded that the 21 patients they sampled "appeared to have sustained injury to widespread brain networks, without an associated history of head trauma." Doctors considered explanations such as a virus or exposure to toxic chemicals but couldn't find any evidence of either one. The only apparent thing the victims had in common was that nearly all of them had heard the strange sound. Nevertheless, the Penn doctors noted that "it is currently unclear if or how the noise is related to the reported symptoms."