Citing an anonymous government official, CNN reports that the USA is still investigating the possibility this was an attack by a third country that might be trying to harm America's relations with Cuba.
Unidentified officials told CNN and other USA media that the staff may have been harmed by a sonic device fired either inside or outside their Havana residences.
Gizmodo reached out to several academic researchers who study hearing loss and our questions about the potential of inaudible sound causing hearing damage were met with confusion. They are responsible for the safety and security of our [diplomat]. Global Affairs Canada said it is working with the United States and Cuba to determine the cause of the odd symptoms. "We took the situation very seriously", he said.
President Obama said "very real differences" on democracy and human rights still exist between the two countries but the best way to address the differences is through engagement.
"The Ministry categorically emphasizes that Cuba has never, nor would it ever, allow that the Cuban territory be used for any action against accredited diplomatic agents or their families, without exception", the ministry said in a statement.
Meanwhile, Washington and Havana had recently re-established ties in 2015, following the 50-year conflict between the two countries.
"The Cuban government has a responsibility and an obligation under the Geneva convention to protect our diplomats", Nauert told reporters, "so that is part of the reason why this is such a major concern of ours".
Meanwhile, Canada confirmed that one of its envoys had suffered a similar incident.
"We are aware of unusual symptoms affecting Canadian and USA diplomatic personnel and their families in Havana", Ms. Maxwell said in an email.
However, officials familiar with the probe said investigators were looking into the possibilities that the incidents were carried out by a third country such as Russian Federation, possibly operating without the knowledge of Cuba's formal chain of command.
The foreign ministry of Cuba, then released a statement saying that they are investigating the allegations, calling the expulsion of its staff unjustified but said that it was willing to co-operate with Washington to clarify what had happened. "And as a result of that, we've asked two Cubans to leave the United States and they have".
But tensions mounted again alive after the detente was partly rolled back by Obama's successor Donald Trump, who won the votes of many Cuban Americans by promising a tough line.
President Donald Trump rolled back part of his predecessor Barack Obama's policy toward Cuba, but has left in place numerous changes, including the re-opened U.S. Embassy in Havana.
"I don't think it could have been the Russians because they, to the best of my understanding, have not restored the kind of military and intelligence cooperation they had with the Cubans before the end of the Cold War".