Bugs blamed for ‘sonic attacks’ on envoys

CUBA: Poorly placed bugging devices may have caused a series of ‘‘sonic attacks’’ that forced the withdrawal of United States diplomats and CIA officers from Cuba a year ago.

Researchers at the University of Michigan have proved that clashing ultrasound devices of the type sometimes used by intelligence agencies can cause the sort of effects that forced the departure of 21 staff and family members from the US embassy in Havana. Some of those forced out reported symptoms resembling brain injuries.

After studying a recording of the alleged attacks, the scientists managed to reproduce a similar effect using listening devices, motion detectors and signal jammers.

They said their experiments demonstrated that a side effect of ultrasound devices installed too close to one another was that their normally inaudible sound waves could clash and could be heard.

Some of the diplomats and undercover agents described hearing unusual, painful noises or vibrations in their private residences and hotel rooms before experiencing nausea, and in a few cases permanent hearing damage. The incidents occurred from December 2016 to January 2017.

The Cuban government has consistently denied any wrongdoing, and has described suggestions that it has a dangerous sonic weapon as ‘‘science fiction’’.

Experts were baffled by the initial reports: a weapon which could emit targeted and damaging sounds as described but was not easily detectable was not known to exist. Ultrasonic or microwave attacks were considered a possible explanation, but they would typically be silent.

The lack of a reasonable explanation led to speculation as to who might have been behind the ‘‘attacks’’. One theory suggested that Russia, North Korea or a rogue Cuban faction was testing a new weapon; another was that the diplomats were suffering from a virus, or even mass hysteria.

The Michigan scientists suggest instead that secondary listening devices placed inside US diplomats’ homes may have clashed with other equipment.

‘‘A malfunctioning device that was supposed to inaudibly steal information or eavesdrop on conversation with ultrasonic transmission seems more plausible than a sonic weapon,’’ Kevin Fu, the lead author of the report, told the Michigan Engineer News Centre.