Record­ing re­veals mys­tery sonic at­tack


WASH­ING­TON • It sounds sort of like a mass of crick­ets. A high-pitched whine that seems to un­du­late, even writhe. Lis­ten closely: There are mul­ti­ple, dis­tinct tones that sound to some like they’re col­lid­ing in a nails-on-the-chalk­board ef­fect.

The Associated Press has ob­tained a record­ing of what some U.S. Em­bassy work­ers heard in Ha­vana in a se­ries of un­nerv­ing in­ci­dents later deemed to be de­lib­er­ate at­tacks. The record­ing, re­leased Thurs­day by the AP, is the first dis­sem­i­nated pub­licly of the many taken in Cuba of mys­te­ri­ous sounds that led in­ves­ti­ga­tors ini­tially to sus­pect a sonic weapon.

Sev­eral Cana­dian diplo­matic per­son­nel were also af­fected this year; the Cana­dian gov­ern­ment says the at­tacks have ap­par­ently stopped.

The record­ings them­selves are not be­lieved to be dan­ger­ous to those who lis­ten. Sound ex­perts and physi­cians say they know of no sound that can cause phys­i­cal dam­age when played for short du­ra­tions at nor­mal lev­els through stan­dard equip­ment like a cell­phone or com­puter.

What de­vice pro­duced the orig­i­nal sound re­mains un­known. Amer­i­cans af­fected in Ha­vana re­ported the sounds hit them at ex­treme vol­umes.

Whether there’s a di­rect re­la­tion­ship be­tween the sound and the phys­i­cal dam­age suf­fered by the vic­tims is also un­clear. The U.S. says that in gen­eral the at­tacks caused hear­ing, cog­ni­tive, vis­ual, bal­ance, sleep and other prob­lems.

The record­ings from Ha­vana have been sent for anal­y­sis to the U.S. Navy and to the in­tel­li­gence ser­vices, the AP has learned. But the record­ings have not sig­nif­i­cantly ad­vanced U.S. knowl­edge about what is harm­ing diplo­mats.

Of­fi­cials say the gov­ern­ment still doesn’t know what or who is re­spon­si­ble for in­juries to its per­son­nel, but the U.S. has faulted Cuba for fail­ing to pro­tect Amer­i­can per­son­nel on its soil. Pres­i­dent Don­ald Trump’s chief of staff, John Kelly, said Thurs­day in re­sponse to a ques­tion: “We be­lieve that the Cuban gov­ern­ment could stop the at­tacks on our diplo­mats.”

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 said.

The record­ing re­leased by the AP has been dig­i­tally en­hanced to in­crease vol­ume and re­duce back­ground noise, but has not been oth­er­wise al­tered.

The sound seems to man­i­fest in pulses of vary­ing lengths — seven sec­onds, 12 sec­onds, two sec­onds — with some sus­tained pe­ri­ods of sev­eral min­utes or more. Then there is a si­lence for a sec­ond, or 13 sec­onds, or four sec­onds, be­fore the sound abruptly starts again.

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.

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 The Ge­orge Wash­ing­ton Univer­sity who reviewed the record­ing with the AP.

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.


At­tacks on diplo­matic per­son­nel at the U.S. Em­bassy in Ha­vana caused hear­ing, cog­ni­tive, vis­ual, bal­ance and sleep prob­lems. The U.S. gov­ern­ment still doesn’t know what or who is re­spon­si­ble for the in­juries.

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