On Thursday, the Associated Press released the first audio recording of the sound that some diplomats say they heard during mystery attacks in Havana, Cuba. Those attacks have so far left 22 Americans with a puzzling range of symptoms, from brain injuries to hearing loss.
The sound is high-pitched and grating. You can listen to it here (but beware: it’s unpleasant).
The noise is composed of 20 or more different frequencies, all around about 7,000 Hz and 8,000 Hz. It reportedly came in abrupt pulses of varying lengths.