“Sort of like a mass of crickets”

Cuban embassy

Image credit: ADALBERTO ROQUE/AFP/Getty Images.

As I have mentioned now and then over the last year and a half, the narrative that American embassy personnel in Cuba were subjected to “sonic attacks” is bullshit (Sonic stupidity“It may seem the stuff of sci-fi novels”; More acoustic credulity; Cuba’s “magical sci-fi sound gun”; No means, no motive, and no suspectMore Cuban science fictionSonic weapons on Skeptoid; FBI dismisses sonic weapons in Cuba “attacks”Asking the wrong questions: still no evidence of a sonic weapon):

There is no evidence that U.S. embassy officials in Cuba were subjected to any kind of attack. There are a bunch of reported symptoms that are not clearly related and mostly subjective. The symptoms are consistent with lots of other explanations; the only reason they’re being attributed to attacks is assertions by unnamed government officials. To my knowledge, none of these assertions are backed by evidence.

This matters, because the sonic attack narrative has had an effect on American foreign policy, serving as an excuse for the Trump administration to pull diplomats out of Cuba and kick Cuban diplomats out of Washington. Why do I call it an excuse? Because long before embassy personnel started getting sick, President (then candidate) Trump promised to roll back Obama-era warming of relations between the United States and Cuba:

Would it be so surprising if President Trump decided to strike while the iron was hot and start breaking diplomatic ties with Cuba while the press was reporting mysterious high-tech weapons being turned on embassy personnel? I’m not even suggesting dishonesty on the part of the President; he’s never struck me as having a particularly skeptical mindset. Why would he ask hard questions when the media was telling him what he wanted to hear?

The only relevant physical evidence we know of that is relevant to this episode is a recording obtained by AP reporters Josh Lederman and Michael Wessenstein back in October of 2017. Researchers from Zhejiang University and the University of Michigan showed back in March that they could produce similar sounds via interference between ultrasonic emitters, which, as I commented at the time, is true but irrelevant:

Note that they only show that the recorded sound, which is not known to be the cause of anything, can be reproduced this way. This is a nice proof of concept, but it is in no way evidence that the diplomats were attacked at all, much less by a sonic weapon. The researchers don’t show, try to show, or claim that there is any way the ultrasound used to reproduce the frequency could have caused any, much less all, of the symptoms experienced by the embassy staff.

Now a new analysis of the recorded sounds has been posted to bioRxiv by Alexander L. Stubbs of UC Berkeley and Fernando Montealegre-Z of the University of Lincoln. Before I get into the content, a couple of caveats. First, this is a preprint; it hasn’t been peer reviewed. Second, the content is too far outside of my field for me to reliably evaluate it. If someone else has expertise in this area, I welcome their comments. Like everything on bioRxiv, the preprint is available to anyone with an internet connection.

The main conclusion of the preprint is right in the title: “Recording of ‘sonic attacks’ on U.S. diplomats in Cuba spectrally matches the echoing call of a Caribbean cricket.” They played recordings of the calls of several insects that live in Cuba and found that, when played indoors,

…the calling song of the Indies short-tailed cricket (Anurogryllus celerinictus) matches, in nuanced detail, the AP recording in duration, pulse repetition rate, power spectrum, pulse rate stability, and oscillations per pulse. The AP recording also exhibits frequency decay in individual pulses, a distinct acoustic signature of cricket sound production.

Stubbs & Montealegre-Z Fig. 1

Figure 1 from Stubbs and Montealegre-Z 2019. Normalized amplitude spectrum of potential sound sources compared to AP recording. a, the AP-released recording from Cuba, b, recording of A. celerinictus played on a speaker and recorded indoors, c, A. celerinictus and d the katydid Neoconocephalus robustus recorded in the field. N. robustus has a broader spectral emission, with more power at higher frequencies, than the cricket A. celerinictus. The distinctive picket fence structure in the amplitude spectrum occurs at integer multiples of the pulse repetition rate (PRR), in this case multiple of 180 for the A.P. recording and A. celerinictus recording with and without echoes. The picket microstructure depends on PRR stability. Any proposed source must conform to both the peak emission at 7 kHz and have sufficient PRR stability to produce this characteristic picket fence structure in the amplitude spectrum.

After a detailed analysis of the sounds, Stubbs and Montealegre-Z conclude,

The following quantitative signal characteristics provide independent lines of evidence to support the conclusion that the sound recorded by U.S. personnel in Cuba is of biological origin:

  1. Carrier frequency of 7 kHz
  2. Pulse repetition rate of 180 Hz
  3. Timescale and amount of pulse repetition instability
  4. Echo phenomenology
  5. Number of oscillations per pulse
  6. Frequency decay of about 1 kHz over pulse duration

Thus, while disconcerting, the mysterious sounds in Cuba are not physically dangerous and do not constitute a sonic attack.

But that’s not the beautiful part of this story. Here’s the beautiful part: when Lederman and Weissenstein reported on the recording they had obtained, way back in October of 2017, do you want to guess how they described the sound? Did you wonder why the title of this post is in quotes? Here it is, the opening line of their article:

It sounds sort of like a mass of crickets.


Stable links:

Stubbs, A. & Montealegre-Z, F. 2019. Recording of “sonic attacks” on U.S. diplomats in Cuba spectrally matches the echoing call of a Caribbean cricket. bioRxiv 510834. doi: 10.1101/510834

Yan, C., Fu, K. & Xu, W. On Cuba, diplomats, ultrasound, and intermodulation distortion. Comput. Biol. Med. 104, 250–266. doi: 10.1016/j.compbiomed.2018.11.012


  1. rjdownard says

    It’s not an implausible idea (I’ve heard how pervasive cicadas can be in some places in the South, and all one has to include is whether certain people, perhaps older diplomats, were more susceptible to the impact than others).

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