Inaudible Sound: The Medical Misuse

To many people, sound is not considered to play a major part in human behavior. Humans prefer to think that emotions are caused either by an internal soul, or at least a complex system of chemicals and electrical impulses in the brain. Anybody can attest to the power of audible sounds from music, nature or other people to affect behavior and emotion. But, there is an entire world of invisible sound that manages to play a major role. The normal human ear can detect sounds up to 20 kHz, a small number considering the vast range of creatable frequency. However, the sound that is not audible could in fact be the most important piece of the puzzle. Not only is inaudible frequency capable of altering emotion and physical health, it is currently being used as a weapon, despite the promising medical applications. 

The use of inaudible frequency to manipulate behavior and emotion may seem like something from a forgotten science fiction movie or from the ramblings of a conspiracy theorist on an internet blog. However, the scientific community has long since recognized the validity of this science for a wide variety of uses. The University of Japan conducted an experiment based on the use of soundwaves to alter brain chemistry and came up with surprising results. The study confirms, “we broadly examined the frequency dependency of the hypersonic effect. We found significant difference in Alpha-2 EEG… associated with HFC below 48 kHz” (Fukushima). This means that the electrical impulses in the brain were greatly affected when the subjects were exposed to certain high frequency sounds. These sounds were played at 48 kHz, well above the audible human range of a mere 20 kHz. This proves sounds that the human ear cannot hear may still be processed by the brain, leading to a wide range of effects.

Now that the effects of inaudible sound on the human brain has been proven to be more than fiction, it is important to understand the everyday impact that inaudible sound can have. The most popular method has been in media, particularly in the horror and science fiction genre. One of the most popular examples comes from the French crime film Irreversible, where the first thirty minutes of the film are full of what is known as “infrasound” (Zarrelli).  Infrasound falls below the human audible range and is known for being able to create fear and dread in the listener. Composed by Thomas Bangalter, later member of Daft Punk, the eerie score throughout the beginning of the movie is meant to pair with disturbing scenes depicting rape and torture. This created a physical response in the viewers creating a sense of dread, nausea and in some cases paranoia. Compounded by the graphic imagery, the film suffered universal backlash upon release and continues to be one of the most controversial films of the century. Famed critic Roger Ebert commented that Irreversible was “a movie so violent and cruel that most people will find it unwatchable.” 

The debate around this film has led to interesting implications of the use of infrasound. Was the movie despised purely for its graphic nature? Or was the use of frequency a factor? It is hard to imagine that a film so reliant on its use of infrasound would become a figurehead for controversy purely by coincidence. The biological impact of such sound cannot be denied and in the case of Irreversible, the power of this art form is made clearly apparent.

However, the unfortunate truth is that the use of infrasound has use for far darker applications than strengthening artistic works. As with any new discovery, the use of inaudible sound has reached a point where the technology can be weaponized. According to the BBC, in 2016, employees working in the U.S. embassy in Havana Cuba began showing symptoms including cognitive impairment and headaches related to swelling in the brain. Employees were later diagnosed with brain damage and in some cases, permanent hearing loss. This type of injury was in line with victims of “acoustic attacks” (Cuba Acoustic Attack), where sound is played at such a damaging frequency that the ear and brain become physically ruptured, resulting in the symptoms that were reported.

Still, none of the victims reported hearing any odd sounds, and the embassy did not have the large speakers required for the use of infrasound. This leads to the possibility that ultrasound was the culprit. Ultrasound acts in the opposite manner as the above-mentioned infrasound. With a sonic range above 20 kHz, ultrasound lies far above the normal human range. And the Japanese study used ultrasound to find the results described earlier. In addition, the equipment needed to deliver ultrasound, amounts to little more than a common P.A. speaker. This strategy is possible within the embassy, where sonic attacks continue to be carried out on Americans within the building. As of October of 2017, the total number of people injured has risen to sixteen people, all injured by a weapon that cannot be seen, felt, tasted or heard. 

Despite the potentially horrifying implication of ultrasound as demonstrated in Cuba, there are positive uses for this technology. The very term “ultrasound” brings to mind the image of a young couple anxiously awaiting a first image of their unborn child. And this is far from the only applicable medical use of ultrasound and infrasound.  According to the International Electrical Contractors, ultrasound not only has applications in noninvasively creating images, but it can also be used for certain types of surgery. By using an ultrasonic surgical instrument, special sound waves produce vibrations that result in an extremely precise cut. This is used for all manner of surgery while lowering the chances of bleeding in surrounding areas (Price). In addition, ultrasound is used to shatter kidney stones, resulting in less pain when passing, and can even break up plaque on teeth resulting in an easy white smile.  

Even with these advancements, one area is being researched that could potentially change the entire field of medicine. By sending ultrasonic waves directly into the brain, Yusif Tufail of Arizona State University discovered that the use of ultrasound can yield shocking results. The study confirms that by stimulating the brain, researchers found that ultrasound can act as a sort of “neurological defibrillator” (Tufail). The sounds used caused nerve endings to jump start while also avoiding a large buildup of heat and concussive force. This could theoretically reshape a person’s brain to effectively cure neurological issues ranging from Parkinson’s disease to depression, all while avoiding dangerous drugs and costly long-lasting therapy. Currently this study is being contained to experiments on lab mice and has yet to move into human testing. This style of treatment will require hundreds of people with different specializations and potentially billions of dollars. However, the result could potentially be one of the largest medical breakthroughs of the century.

The use of inaudible sound carries unbelievable potential from countless medical applications to increasing the power of art. However, the unfortunate truth remains that there is far more information regarding sound as a weapon than there is sound as medicine. Some studies have been conducted in the field of sonic medicine, however they make slow progress due to lack of funding. Sonic weaponry on the other hand, is heavily funded. This stems from humanities desperate need to show power instead of curing deeper issues. Higher powers of society choose to take this limitless potential and apply it to a form of destruction. While staying powerful is important to any country, society already has plenty of technology capable of killing. A disease such as Parkinson’s has inflicted harm on people for decades, with no real cure in sight. Now that the ability to cure it nears, it would be wise to make it priority number one.

Inaudible frequency and its potential continues to gain validity. And while it has found an applicable foothold in multiple scientific communities, it has yet to truly reach its fullest potential. The use of this technology for military applications is a potentially useful one, however, this is a waste of the overall application of sound. Modern medicine has come a long way. However, diseases remain; particularly mental disorders that cannot be touched by modern treatments. Inaudible sound may very well act as the missing piece for curing these issues, and therefore requires further research.

Works Cited

Fukushima A, Yagi R, Kawai N, Honda M, Nishina E, et al. (2014) Frequencies of Inaudible High-Frequency Sounds Differentially Affect Brain Activity: Positive and Negative Hypersonic Effects. PLoS ONE 9(4): e95464. doi:10.1371/journal.pone.0095464.

Zarrelli, Natalie. “How the Hidden Sounds of Horror Movies Freak You Out.” Accessed October 3 2017.

Ebert, Roger. Irreversible. Accessed October 3 2017.

“Cuba Acoustic Attack.” Accessed October 3 2017.

Price, Antoinette. “Ultrasonics in medical applications.” 014-08/Ultrasonics-in-medical-applications. Accessed October 10 2017.

Tufail, Yusuf, Baldwin, Nathan, Taucman, Monica, et al. “Transcranial Pulsed Ultrasound Stimulates Intact Brain Circuits.” . Accessed October 13 2017.


Jessy Lee Stuebs is a professional musician and Colorado Springs local. In between practice, tinkering with various music equipment and recording, he reads about new technologies, laughs at conspiracy theories and talks history and politics with anybody who will listen.