What Are Sound Weapons?

Attacks on Americans in Cuba are calling attention to how inaudible sound waves can alter moods and perceptions.

An artist's rendering of a sonic boom
(Jupiterimages / Getty)

Earlier this month the U.S. State Department disclosed that several Havana-based diplomats have experienced “incidents which have caused a variety of physical symptoms.” Secretary Rex Tillerson said the incidents began last fall, calling them “health attacks.”

They were not the good kind of health attacks. Symptoms have included severe hearing loss, headaches, and problems with balance—forcing some diplomats to return to the United States. “We hold the Cuban authorities responsible for finding out who is carrying out these health attacks,” Tillerson said.

His remarks came after a search for the cause of the symptoms—also reported among Canadian diplomats living in Cuban housing—led some U.S. officials to conclude that the weapon is inaudible sonic waves.

This morning journalists at CBS reported that the diplomats’ medical records indicated that they had undergone audiological evaluations and a battery of other tests, and that there was documented concern for the possibility that they “were targets of a type of sonic attack directed at their homes, which were provided by the Cuban government.” The analysis coincides with reports from the Associated Press earlier this month: “After months of investigation, U.S. officials concluded that the diplomats had been attacked with an advanced sonic weapon that operated outside the range of audible sound and had been deployed either inside or outside their residences.”

Cuba has denied what would be an unprecedented breach of obligation to protect foreign diplomats, and not to blast them with acoustic energy. But exposure to sound waves would be a plausible explanation for this constellation of vague symptoms unified by a relationship to the inner ear.

It is indeed possible to weaponize energy waves with frequencies outside the range that the human ear can detect. The concept is not new, and it has a rich history in science fiction. Weaponization of sound was a plot point in the book that Secretary Tillerson has called his favorite, Ayn Rand’s 1957 novel Atlas Shrugged. In it, the federal science institute creates a weapon of mass destruction which deploys ultrasonic waves. The head of state uses the device to flatten a goat in a demonstration of power, and later to destroy the work of industrious private inventors, successfully stifling private-sector innovation.

The health effects of exposure to inaudible sonic waves are also real. In 2001 after residents of Kokomo, Indiana, began reporting symptoms including “annoyance, sleep disturbance, headaches, and nausea,” the U.S. National Institutes of Health investigated the issue. The result was a dossier on the toxicology of “infrasound”—acoustic energy with wavelengths of 17 meters or more. The agency couldn’t pin down the cause of the Indiana residents’ symptoms as infrasound, but the report did confirm that infrasound can cause fatigue, apathy, hearing loss, confusion, and disorientation. In one study cited therein, volunteers exposed to industrial infrasound for just 15 minutes reported fatigue, depression, pressure in the ears, loss of concentration, drowsiness, and “vibration of internal organs.”

While infrasound would seem to be a possible and plausible mechanism of the “health attacks” in Cuba, CNN has also reported that some incidents were accompanied by audible noises—“deafeningly loud sound similar to the buzzing created by insects or metal scraping across a floor.” The mechanism in that case would be less subtle. Deafeningly loud sound is so called because it either ruptures the eardrum or jolts the tiny bones of the middle ear.

At the same time, CNN also posits, “The sophistication of the attack has led U.S. officials to suspect a third country is involved, perhaps seeking payback against the United States and Canada or to drive a wedge between those countries and Cuba,” raising the possibility of operatives from Russia, China, North Korea, Venezuela, or Iran.

It's not clear why these attacks would qualify as sophisticated. Noise-induced hearing loss affects around one in four people—only, usually, it’s due to lower-level exposures over years, from attending concerts, shooting guns, and being too cool to cover one’s ears when an ambulance screams past on the street. While the investigation in Havana unfolds, fascination with this sort of attack can be a reminder that it is worth arming ourselves in daily life against the more quotidian forms of sonic weaponry.