Back in October, AP reported that they had “obtained a recording of what some U.S. Embassy workers heard in Havana,” a high-pitched whine “sort of like a mass of crickets.”
A new technical report tests the idea that the audible sounds recorded by AP in Cuba could have been caused by two (or more) ultrasonic sources (a less technical description is here). What the paper shows is that sounds similar to those in the AP report can be produced from the interference of one ultrasonic source on another. This much seems convincing. I don’t have a deep understanding of the physics, but the real-world demonstration is hard to argue with.
But just because the sound can be reproduced this way doesn’t mean it was produced this way. I have seen “Eye of the Tiger” played on dot matrix printers. That doesn’t mean Survivor recorded it using dot matrix printers.