U.S. officials have concluded that American diplomats in Cuba were exposed—deliberately, they claimed—to harmful, high-frequency sounds that caused hearing loss, headaches and nausea.
The sonic attacks compelled some diplomats to leave Cuba, the officials said. A Canadian diplomat also reported suffering hearing loss while working in Havana.
The alleged sound-based assaults are just the latest chapter in a long history of sonic warfare dating back millennia.
3,500 years ago, according to Biblical legend, an Israelite army blew trumpets and toppled the walls of Canaanite city of Jericho. Most historians agree that the Biblical account of the Battle of Jericho is fiction. But they also agree that weaponized sound has played an important role in combat and espionage throughout human history, perhaps inspiring the Jericho myth.
New technology promises more dangerous sonic assaults in coming years. "Frequency-based warfare will become more widespread due to its capacity to be covert and controlled from distance," Toby Heys, a media professor at the Manchester School of Arts in the United Kingdom, told The Daily Beast.
Sonic tactics often take the form of music. Think armies marching into battle with drummers, trumpeters or pipers in order to motivate their own troops ... and intimidate the enemy.
"It can be used to confuse the enemy and make him uncomfortable," Herbert Friedman, a retired U.S. Army sergeant major and psychological-warfare expert, told The Daily Beast. "Music that is odd and seems a jumble of sounds can make one almost nauseous and dizzy. It is physical and psychological."
Friedman said that during the German siege of the Soviet city of Stalingrad in 1942, Soviet troops deployed huge loudspeakers and played Argentine tangos at maximum volume in order to keep the Germans awake at night.
57 years later, during the U.S. invasion of Panama, strongman Manuel Noriega barricaded himself in the Vatican's Panama City embassy. U.S. troops blasted rock music at the embassy until Noriega surrendered.
In 2014, Russian agents broadcast propaganda at Ukrainian troops just across the Russia-Ukraine border. The Ukrainians fired back with their own broadcasts ... of music by pop star Cher.
Intelligence agents and military prison guards have deployed sonic assaults in a more intimate -- and sinister -- setting. "Loud music in a POW camp can keep the prisoners from communicating by mouth or tap codes," Friedman said. "We can also keep the prisoner awake which weakens his will to resist."
For sonic attacks in audible frequencies, volume matters most. "It is not so much what kind of music as how loud," Friedman said, adding that the CIA considers 100 decibels -- roughly equivalent to a rock concert or a jackhammer -- "acceptable and not a crime," as long as the sound lasts no longer than two hours.
In the early 2000s, a San Diego company developed a custom-built sonic weapon—the Long-Range Acoustic Device. The LRAD, which looks like a home satellite dish, fires an adjustable, focused beam of sound for what the company describes as a "safer alternative to kinetic force."
At the highest settings, the LRAD emits a 160-decibel whine that, after a few seconds, can induce dizziness and even vomiting in people hundreds of yards away. The LRAD is popular with militaries, police forces and even shipping companies, which install them on commercial ships to defend against pirates.
Friedman said the Cuban attack could have been pulled off with a device similar to the LRAD, but operating at a higher frequency. Such assaults -- subtle and essentially undetectable -- could become more common. "The warfare will not be sonic," Heys warned. "It will be ultrasonic and infrasonic ... those frequency ranges that exist at the edges of perception."