Were infrasonic acoustic weapons used in Venezuela? (Updated Jan 25 2026)

enezuelan soldiers are claiming that during the recent assault on Maduro they were hit with some unknown weapon that caused nosebleeds, vomiting of blood, and dizziness which resulted in an inability to stand or walk.

One site quotes a guard as saying “At one point, they launched something; I don’t know how to describe it . . . It was like a very intense sound wave. Suddenly I felt like my head was exploding from the inside.” The reporter speculated these symptoms most closely match the so-called “thunder generator” shockwave system, which is allegedly designed to incapacitate in a non-lethal manner.

Effects of infrasound on humans

Just how dangerous are infrasonic sound waves? The consensus has long been that infrasound from ventilators and windmills is annoying but not hazardous. But any form of energy can be hazardous at high enough intensity. Liu et al. ^[1] quote a master’s thesis by J. Shi at the 4th Military Medical University in Xincheng as saying:

When the sound intensity reaches 140 dB, regardless of the exposure duration, congestion of the pia mater, subarachnoid hemorrhage, and cortical petechial hemorrhage can be observed in brain tissue.

Petechial hemorrhage is small dots of blood in the tissue caused by rupture of capillaries. Subarachnoid hemorrhage is a type of stroke that has a mortality rate of 8–67%. A sound level of 140 dB might not seem high, but for a pure sine wave it would cause resonant vibrations in the relevant brain structures. The vertigo reported by the guards is consistent with a sonic weapon, which affects the vestibular system at higher frequencies of 16 Hz, while 8 Hz primarily effects hippocampal and cerebral cortex neurons.^[2]

Infrasound can also be used therapeutically, for instance in promoting bone repair and wound healing. ^[3]

Feasibility of brown-note weapons

Infrasonic acoustic weapons have been suggested for decades, including for the Havana syndrome, but they have many unsolved practical problems. The biggest one is how to focus the beam.

Low frequency sound doesn’t propagate directionally. Unless the operator and all his comrades were in a soundproof chamber, the pressure waves would affect them as much as the target. Any focusing device, whether by a reflective dish or by phase canceling, would require a structure with geometry on the order of multiples of a wavelength. At 20 Hz, the wavelength is 56 feet. At 8 Hz, the wavelength is 140.6 feet.

To create a beam that can be focused less than 180 degrees, the sound waves would either need to be generated incidentally, perhaps as a side effect of something that can be directed, like microwaves, or generated by some process like a chemical reaction close to the target.

Ultrasound is easy to focus, but anyone who has worked with ultrasonic waves knows that their subhar­mon­ics (‘squeaking’), while annoying and hazardous to hearing, are clearly audible. The same challenges would occur from modulated microwave beams.

One possibility might be to take advantage of the tendency of sound to follow wind patterns. Sound obeys Snel’s (sometimes spelled Snell’s) law and sound waves will curve across a velocity gradient.^[4] You can more easily hear someone if they’re upwind than if they’re downwind. A crosswind between two people can make acoustic communication impossible. So it’s conceivable that an infrasonic beam could be contained by surrounding it with powerful blast of air, much as the cladding of an optical fiber contains a laser beam.

A challenge is that effective shielding might require a very high air velocity, possibly high enough to create a sonic boom, which would be audible. A high velocity would also cause turbulence, which would disrupt the shielding.

There are more sophisticated infrasound waveguides in the acoustics literature. Watkins and Bilal proposed using tunable lattices of repelling magnets to guide infrasound waves.^[5] But these are primarily for detection of meteors, volcanoes, and similar phenomena.

Concussion grenades

Finally, it might be possible to generate infrasound at the target by using special projectiles designed to generate loud noises, for example by igniting a propellant after a fixed time. These are called concussion grenades and the military has used them for years. This would likely be broadband sound at frequencies below 3 Hz^[6] in addition to a shock wave, not the monochromatic infrasound that is needed. These authors found high-energy infrasound at 1.987, 2.296, 2.528, and 6–10 Hz. Only small amounts (0.2 psi) of overpres­sure transients, called N-waves, were observed. The authors say the infrasound caused headaches, nausea, dizziness, trouble sleeping, and extreme fatigue that can last for days.

Why reveal this weapon now?

If long-term harmful effects of infrasonic weapons were proven, revealing them could result in banning by the Geneva Convention or the Vienna Protocol, which bans lasers capable of causing blindness. There is also risk that disclosure would encourage adversaries to develop similar weapons, if they have not already done so.

But concerns about proliferation might be outweighed by the deterrent factor. It may be significant that most of the security personnel guarding Maduro were not Venezuelans but Cubans. One might then speculate that this sonic attack could be payback for the alleged US embassy attacks; or a warning that the USA has now invested resources into this type of weapon and is willing to use it. If the US government already had such a weapon, it might explain their reluctance to find the cause of the Havana syndrome.

Given the technical challenges, however, maybe we should reconsider the Cubans’ suggestion that the Havana syndrome was actually cicadas. How sure are we that these guards weren’t just hearing tropical cicadas? One problem with this theory is that a cicada emits sound at about 2 kHz. To get it to 20 Hz, the cicada would have to be about 16 feet long.

US helicopters releasing giant 16-foot man-eating cicadas. The press will love it.

jan 12 2026, 7:51 am. updated jan 25 2026 to add discussion of concussion grenades