I will try not to go too far out of my realm of limited expertise on this subject.
About 18 months or so ago a buddy of mine and I collaborated on an "open" publicly advertised request by DARPA to design a device useful to terrorism that could be built using only DIY and OTC materials and that significantly defeated modern security. We decided at the time that we were going to build a SAM unit that could use a mixture of range finding trig and speed calculations to fire a missile and low and slow targets. However, we ended up scrapping that initial approach and tried to go laser guidance (because lasers are cool, right?) when that didn't work out, we came to the decision that we would use infrasound beams to guide the missile on target, as it could not be defeated by conventional counter measures designed to beat laser guidance. I won't get too much into the technical details of that, but the short version is that you can't hear it and it won't reflect off of IR coatings or pop hot on laser detectors.
The problem was how to make it safe for the operator, you know, not deafen them. So my friend, brilliant guy that he was, found some other related tech that more or less uses the same concept as a gamma knife or a solar focusing array, maybe. Essentially, there are ways to have two (or more, really) emitters, and both will output safe levels of sonic energy, up until the point where you "cross the streams". The sound generation can be localized on target or, in the case of our needs, was intended to be used to build a "tube" of acoustic energy around the guidance path we wanted our missile on. For a variety of reasons mostly related to the fact that the DARPA site is a nightmare to navigate and the BAA they put out was about as clear as one way glass, we never submitted our design (which is a shame, because I think it was actually a pretty good idea) but the first thing I thought when I read about this was that it was probably someone using a system for localizing sound in the infra sound range.
Anyway, relevant ted talk about what I mean, although this focuses more on the ultrasound range.
https://www.ted.com/talks/woody_norr...amazing_things
Edit: I kind of started waxing philosophical and got off my main point. There's really not a whole lot in this for cuba. I'd bet it was either a third party, or an NGO/Terror group. There's enough publicly available information out there to DIY a system of this capability. Why is something I can't answer.