Two employees at the US embassy in Havana have been sent home after suffering hearing loss from a silent "acoustic attack."

From http://www.cnn.com/2017/08/09/politics/us-cuba-acoustic-attack-embassy/index.html:

The sophisticated device that operated outside the range of audible sound was deployed either inside or outside the residences of US diplomats living in Havana, according to three US officials.

The Cuban government says it had nothing to do with the attack.

From Time: