Have you ever wondered what sound looks like?
Most of us are keenly aware that you can’t see sound. We understand that sound is nothing more than complex patterns or waves of air compression, travelling over a distance and ultimately causing the small bones in our ears to vibrate, which we perceive as music, or a dog barking, or the voice of a loved one. Sound isn’t a tangible thing, in the sense that one could ever grab hold of it, or experience it in any other way. But then, as my favourite author once mused… reality is frequently inaccurate.
As the story goes, on July 8 of the year 1680, English polymath and academic, Robert Hooke, conducted an experiment of sorts. He used a musical bow on the edge of a glass plate covered in flour. As he drew the bow across the edge of the plate, he noticed patterns forming in the flour. In scientific terms, what he saw are called nodal patterns, which are, essentially, the strange geometric shapes that formed within the grains of flour in response to the vibrations. Which means, those shapes and patterns are a visual representation of sound.
Hooke’s experiment was repeated a number of times, always with the same result, but it wasn’t until the mid-to-late 1960’s that Swiss doctor and Anthroposophist (a philosophical adherent to Rudolf Steiner’s writings), Hans Jenny, undertook to methodologically quantify what Hooke had started.
Jenny coined the term Cymatics, and through his work attempting to identify and accurately describe the mechanism of Cymatics, he pioneered the use of piezoelectric crystals in scientific applications to create and finely control sound vibrations in the metal plates he used. Which is interesting, but neither here, nor there.
Now, visual sound co-vibration, which is the technical term for the product of Cymatics, hasn’t directly offered much in terms of real-world applications, though it has become an art form all its own. Artists use many different mediums to achieve truly beautiful images, like coloured sand, granulated glass and even water. Indirectly, the study of nodal patterns has drastically advanced several fields related to engineering. Cymatics was the precursor to every engineering technique that uses or guards against vibration of any kind; from sound-proofing, to earthquake resistance. And it has recently come to the forefront of science news again.
You may remember recent headlines about scientists using a bag of chips to spy on conversations with a very sensitive camera. They achieved astounding results; results that were previously the domain of science fiction only.
If you’ll recall what may have been Shia Lebeouff’s last successful role, in the movie Eagle Eye the US Army’s secretly developed, Artificial Intelligence, super-computer used security cameras to spy on a secret meeting between investigators and the Secretary of Defense. She (the computer) observed the minute vibrational patterns (nodal patterns) on the surface of water in a glass to decipher what was being said out of her field of view.
Many who saw that movie may have thought such a thing to be a relatively simple endeavour, but they would be mistaken. Developed by researchers at MIT and presented at the Siggraph 2014 conference this spring, an algorithm has been designed to translate the nodal patterns of vibration on most common surfaces that are caused by speech sounds. Which means that those with the means can spy on any conversation held in view of a camera by way of detecting these patterns in or on objects in the room.
See? Astounding. And all of that is possible because of Robert Hooke’s early work in Cymatics.
It’s interesting though, that all of this potential for James Bond-type action, is actually due to sand. Or, well… grains of particulate resting on a vibrating surface. This isn’t the only way sand relates to sound though.
If you live in a desert, you may be familiar with what follows, though maybe not by name.
Singing sand, or sometimes called barking sand, is actually just what it seems. Sand of specific dimensions and ingredient, and in certain conditions can sing when wind blows across it, or even when it’s stepped on.
You may be reading this with a touch of incredulity at the moment, but rest assured, this is a real thing.
The resulting sound, which has been unofficially dubbed the song of the dunes, is said to be a loud, low-pitched rumble or roar. It’s known to be as loud as 105 decibels and can last for upwards of a minute, typically at a frequency of 450 MHz.
In order to produce the effect, the sand must have round grains between 0.1 and 0.5mm in diameter, and must contain a large percentage of silica. A specific humidity level is also required.
Surprisingly, there are many locations around the world, including many in the United States, that offer this singing sand, or singing dunes. The famous Kelso Dunes of California, Sand Mountain in Nevada, the Booming Dunes in the Namib Desert of Africa, and the barking sands of Hawai’i, just to name a few.
It seems fairly obvious that such phenomenon would have found its way into local legends and folklore over the centuries, and perhaps it has. Could the Native American legend of the Thunderbird have been caused, even partially, by singing sand? Is, perhaps, the mysterious hum heard by millions of people around the world actually, even just in some cases, the result of barking dunes? As with any such mystery, it’s important to consider all of the possibilities, and this one seems viable.
As mentioned above, the sound frequency normally associated with singing sand is 450 MHz, but it has been recorded at frequencies between 60 and 105 MHz, and this coincides in a strange way with another weird phenomenon.
Discussed here, the scientific field of archaeoacoustics – which endeavours to study, explain, and apply the effects of sound as it relates to ancient rock art and architecture – along with research into the effects of sound on human cognition, neural activity, and altered states of consciousness, have determined, with some room for interpretation, that tonal sounds within the frequency range of 90 to 120 MHz have the effect of inducing brain states that are similar to those achieved through meditation, and even through the use of psychotropic drugs.
With this information in mind, is it possible to attribute the common calming effect of laying on a beach to the action of singing sand? Perhaps not, at least not in the sense that the universality of our love for beaches is due to rumbling sand, but it might be worthwhile considering its small potential contribution.
However you choose to look at it, it’s becoming apparent to science, as it has been to music lovers for ages, that sound is just as important as all we can see. In any event, we ought to pay more attention to what we hear.
 Abe Davis, et al. The visual microphone: passive recovery of sound from video. Journal – ACM Transactions on Graphics. July 4, 2014. doi>10.1145/2601097.2601119