Recording is released of high-pitched sound Americans heard in Cuba
WASHINGTON – It sounds sort of like a mass of crickets. But not quite. A high-pitched whine, but from what? It seems to undulate, even writhe. Listening closely, some hear multiple, distinct tones colliding in a nails-on-the-chalkboard effect.
The Associated Press obtained a recording of what some U.S. Embassy workers heard in Havana, part of the series of unnerving incidents later deemed to be deliberate attacks. The recording is the first disseminated publicly of the many taken in Cuba of sounds that led investigators initially to suspect a sonic weapon.
The recordings from Havana have been sent for analysis to the U.S. Navy, which has advanced capabilities for analyzing acoustic signals, and to the intelligence services. But the recordings have not significantly advanced U.S. knowledge about what is harming diplomats. Officials say the government still doesn’t know what is responsible for injuries to its personnel.
White House chief of staff John Kelly said Thursday that the United States believes the Cuban government could stop attacks on U.S. diplomats. He didn’t elaborate.
Previously, the United States said merely that it was Cuba’s responsibility under international law to protect diplomats serving on its soil. Cuba has denied involvement in or knowledge of the attacks.
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 highpitched sound. Individuals who have heard the noise in Havana confirm the recordings are generally consistent with what they heard.
“That’s the sound,” one of them said.
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.
Whether there’s a direct relationship between the sound and the physical damage Online: suffered by the victims is unclear. The U.S. says that in general, the attacks caused hearing, cognitive, visual, balance, sleep and other problems.
A closer examination of one recording reveals it’s not just a single sound. Roughly 20 or more different frequencies, or pitches, are embedded in it, the AP discovered using a spectrum analyzer, which measures a signal’s frequency and amplitude.
To the ear, the multiple frequencies can sound a bit like dissonant keys on a piano being struck all at once. Plotted on a graph, the Havana sound forms a series of “peaks” that jump up from a baseline, like spikes or fingers on a hand.
“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 George Washington University who reviewed the recording.
Those frequencies might be only part of the picture. Conventional recording devices and tools to measure sound may not pick up very high or low frequencies, such as those above or below what the human ear can hear. Investigators have explored whether infrasound or ultrasound might be at play in the Havana attacks.
The recordings have been played for workers at the U.S. Embassy to teach them what to listen for, said several individuals with knowledge of the situation in Havana. Some embassy employees have also been given recording devices to turn on if they hear the sounds.
The recordings have been played for workers at the U.S. Embassy in Havana to teach them what to listen for. To listen to the recording, go to startribune.com