You've probably heard about this already. I've been reading about this on various sites for weeks now. Most mainstream news sites are heavily implying if not outright saying that it's an attack. I've heard all kinds of wacky theories, ultrasonic, infrasonic, maser, pulse gun, etc.
Scientists I've read from are skeptical for the most part, but most people including news orgs seem to have seen one too many James Bond movies.
The AP seems skeptical enough for a news org, and they've released the supposed audio: https://apnews.com/88bb914f8b284088bce48e54f6736d84
Not all Americans injured in Cuba heard sounds. Of those who did, it’s not clear they heard precisely the same thing.
Yet the AP has reviewed several recordings from Havana taken under different circumstances, and all have variations of the same high-pitched sound. Individuals who have heard the noise in Havana confirm the recordings are generally consistent with what they heard.
The sound seemed to manifest in pulses of varying lengths — seven seconds, 12 seconds, two seconds — with some sustained periods of several minutes or more. Then there would be silence for a second, or 13 seconds, or four seconds, before the sound abruptly started again.
“What it is telling us is the sound is located between about 7,000 kHz and 8,000 kHz. There are about 20 peaks, and they seem to be equally spaced. All these peaks correspond to a different frequency,” said Kausik Sarkar, an acoustics expert and engineering professor at The George Washington University who reviewed the recording with the AP.
Smells of Yellow Cake
I think the IMD would be pretty obvious from any sort of focused ultrasound powerful enough to have physiological effects.
AP now says:
"An earlier version of this story incorrectly described the sounds as being between 7,000 kHz and 8,000 kHz. That sentence has been deleted."
I wonder why they deleted it, maybe they couldn't be sure it was only in that range. In any case, lots of conflicting anecdotes, some heard it, some didn't hear anything... Seems to me a sound attack is the least plausible of theories.
I have also seen news media considering the possibility that this might be a case of 'mass hysteria (https://en.wikipedia.org/wiki/Mass_hysteria)'. That would also explain why it only affected some people and not others, neighbours for instance. If it was a weapon in the shape of some kind of sound waves canon aimed at the building you'd expect it to operate pretty indiscriminately.
I remember a case in Belgium some time ago where dozens of people, mainly teenagers I believe, were hospitalised after having drank Coca Cola that was suggested to have been poisoned/contaminated. People had symptoms and all but no evidence of any relation to their consumption patterns or anything peculiar about those batches of coke was ever discovered.