Transcript for New developments in the mystery attacks of US diplomats in Cuba

We' Now, new developments in the mystery attack on American diplomats and their families in Cuba. Claiming some suffered brain injuries and permanent hearing loss. Here's David Kerley. Reporter: Word tonight that some American diplomats serving in Cuba not only suffered mild traumatic brain injuries, but also some with permanent hearing loss. The foreign service association saying it met with ten of those affected. Who were hit by the sonic harassment attacks. Along with traumatic brain injury, some officers are experiencing loss of balance, severe headaches, and cognitive disruption. A source says starting last December, the U.S. Officials were exposed to a sonic device which experts suggest cold produce sound waves below, and above human hearing which could cause these symptoms. Some officials were medically evacuated. The news tonight coming from the officers' union, not the state department which refused to reveal the diagnosis, but did expel two Cuban diplomats in retaliation. We hold the Cuban authorities responsible for finding out who is carrying out these health attacks. Reporter: Cuba says it has never used or allowed its territory to be used to attack diplomats. Tonight, the state department says the number of people affected stands at 19, the most recent, just a month ago.

This transcript has been automatically generated and may not be 100% accurate.