The causes of hearing loss are pretty much well known. And presumably—because of the long history of Fidel Castro’s behavior and today’s less-than-relaxed relationship between the U.S. and Cuba—most of the tricks that could have been played have already been played. However, it is well known that Cuba has excellent health care. So presumably there is good medical knowledge in Cuba, which could well extend to knowledge of poisons and procedures that could have been used to cause hearing loss. What is scary, however, is that U.S. and Canadian medical experts have thus far been clueless as to the cause of the diplomats’ hearing loss that was announced on August 10. Shame on the US and Canada if they are bested by Cuba on ANY aspect of technology, though perhaps it was technology invented by the Fidel Castro regime to maintain his control of Cuba (“hear no evil see no evil speak no evil”). One thing that has not been mentioned in all of the press accounts is the possible effect of low-frequency (20-250 Hz (cycles per second)) sounds.
However, Cuba may have some motivation to punish the U.S. because Trump has (predictably) reversed some of the actions of Obama.