Doctors and scientists believe weapons using microwave radiation likely were used to attack American diplomats and their families in Cuba and China, and say they are sure that those affected have suffered brain injuries.
"Everybody was relatively skeptical at first, and everyone now agrees there’s something there," Dr. Douglas Smith, the lead author of a report from a medical team that examined 21 affected diplomats from Cuba, told The New York Times.
The report, published in the Journal of the American Medical Association [JAMA] in March, did not mention microwaves, but Smith, who is director of the Center for Brain Injury and Repair at the University of Pennsylvania, said the team's opinion has been changing.
He noted that the diplomats and doctors have been calling the injuries the "immaculate concussion."
Analysts are citing a phenomenon called the Frey effect, named for American scientist Allan Frey, who found years ago that microwaves can make the brain perceive what seems to be sounds.
When microwaves enter the ear, they make a person's eardrum vibrate, and eventually, the brain’s temporal lobes receive vibrations that are translated into sounds and speech.
This explains reports of the painful sounds, including ringing, buzzing and grinding that some of the diplomats say they experienced, say analysts.
The State Department said the investigation hasn't yet identified the source or cause of the attacks, and the FBI has declined to comment on the investigation or theories about microwaves.