Vanity Fair has the article The Real Story Behind the Havana Embassy Mystery. I think this is the story the internet is citing as the idea that the cause was crickets. Here is the excerpt that mentioned crickets.
And, in fact, once experts listened to the YouTube recording, there was an almost embarrassing revelation. What did many hear? Crickets.
Literally, crickets. Specifically, Gryllus assimilis, a.k.a. the Jamaican field cricket, also known sarcastically among bug experts as the “silent cricket.” And while Gryllus can get as loud as, say, a vacuum cleaner, it’s not noisy enough to cause deafness. Or, others argued, the sound might be cicadas. ProPublica’s groundbreaking investigation into the embassy mystery last winter quoted a biology professor named Allen Sanborn as saying that the only way a cicada could injure your hearing was if “it was shoved into your ear canal.”
In my scanning the article, I don’t think it is really postulating that crickets are the cause. However, crickets sounds cute as a meme going around the internet. Read the article your self, to see if you can figure out the most likely cause raised in the article. I thiink a Cuban attack is pretty thoroughly ruled out.
This excerpt gets to what I think the article is concluding as the cause.
“Think of mass psychogenic illness as the placebo effect in reverse,” says Robert Bartholomew, a professor of medical sociology and one of the leading experts on conversion disorder. “You can often make yourself feel better by taking a sugar pill. You can also make yourself feel sick if you think you are becoming sick. Mass psychogenic illness involves the nervous system, and can mimic a variety of illnesses.”
The article mentions another term that we might be more familiar with.
As it happens, there is and always has been one mechanism that produces precisely this effect in humans. Today it’s referred to in the medical literature as conversion disorder—that is, the conversion of stress and fear into actual physical illness. But most people know it by an older, creakier term: mass hysteria. Among scientists, it’s not a popular term these days, probably because “mass hysteria” summons the image of a huge mob, panicked into a stampede (with a whiff of misogyny thrown in). But properly understood, the official definition, when applied to the events in Havana, sounds eerily familiar. Conversion disorder, according to the International Journal of Social Psychiatry, is the “rapid spread of illness signs and symptoms among members of a cohesive social group, for which there is no corresponding organic origin.”