The Universal Sense (27 page)

But a “statistically significant portion of a population” represents a healthy demographic for marketers. This is probably why news and media outlets are replete with stories and ads full of such buzzwords as “neural marketing,” “consumer brain scanning,” and “targeted ads” and discuss the use of such diverse neuroscientific gear as eye trackers, EEGs, and even fMRI. If applied properly, such things can provide insight into purchasing decisions. (At least purchasing decisions made while covered in electrodes or strapped onto a gurney in a narrow tube with 100 dB sounds being made around your head for twenty minutes. A fluffy bunny jumper? Yes, I’ll take two—
just get me out of here!
) But it’s not all about marketing and sales. What if these targeted brain hacks were applied to create a calming sound field in a stressful environment, such as a hospital waiting room or an airport waiting area? Or if spatial sounds were applied to limit motion sickness on transportation? Or if sleep-inducing sounds were played for post-surgical hospital patients to help them recover faster? This is the beginning of the next age not only in understanding sensory and auditory processing in the brain but in making it useful in the real world. We have just begun to realize the practical potential of all the data collected in the thousands of neuroscience labs across the world. And just as sound has been with us from the start, it will help us define the future of our technology, and our lives.

Chapter 9
Weapons and Weirdness

Shortly after leaving Columbia University in 1981 as an undiplomaed junior (and having been told I had no future in science by one of my biology professors), I was working as a gigging musician. I had just bought my first synthesizer, an old analog Juno 106, which, as was typical in the primeval technological era of the 1980s, was no more digital than the cockroaches that infested my apartment. I was trying to figure out if it was possible to create fractal sounds—a largely theoretical construct at the time involving generating recursive tones that modified themselves in real time. Given the technology of the time, there was no way to change parameters on the fly using software—I was stuck just using the analog oscillators, filters, sliders, wheels, and other quaint manual controllers. The Juno was connected to a very old, rather noisy, but very, very big amplifier.

I had just spent an hour moving the controls to very precise positions to try to convince the oscillators to go in and out of sync while simultaneously shifting the low-frequency oscillator to act as a filter cutoff when my cat jumped on the control panel, rearranging things more to his liking. He then left at high speed,
probably inspired by a very loud, very frustrated non-fractal vocalization on the part of his owner. Once I calmed down, and upon realizing that the cat probably had as much of a chance of coming up with fractal sounds as I did with this system, I pressed a single key. The amplifier gave out a very loud, weird sound, a low-frequency, high-powered beating thrum. It wasn’t so much fractal as nauseating. I started to feel strange. So I turned to face the amp. And I threw up.

After cleaning up after myself, the amp, and the cat, all I could think was, “What the hell was
that
?” Somehow the cat and I accidentally made a sound that had a
very
non-auditory effect. Years later I was trying to assure a student that there was no such thing as the “brown sound,” a legendary tone that was supposed to make you lose bowel control, when I remembered that scene. I started slowing down in my explanation about how sound was just something you heard and it couldn’t affect your intestinal tract or your body, until finally, mumbling something about having to get to another class, I started wondering about the secret, sometimes classified aspects of sound.

Humans have a strange relationship with sound. We ignore most of it, shuffling it around in our brain stem to be monitored as “background,” something that sets the stage of our world, driving attention but rarely capturing it. Yet even as we ignore it, it sits under our mind, doing all sorts of things that bubble up to our consciousness only after we put it in context of the rest of our senses and environment. It’s the sensory system that runs in the dark, out of line of sight, telling you not so much what something is but that something important to your survival happened. Perhaps that’s why humans often ascribe powers to certain types of sound, as if the waves themselves were alive and had intentions, good and bad.

Sound has long pervaded human cultures, linking us to the world. The Bible dictates that the world was created when God
said
, “Let there be light”; Hindus believe in the creative vibration of the syllable “om”; and the Huang Chung or “yellow bell” served as the primal tone of the scale that defined the relationship between the ancient Chinese imperial court and the harmony of the universe. This tendency runs under everything we do, from religion to pop culture, from science to military matters. And as with any tool humans pay enough attention to and play with long enough, these powers often get turned to dark uses. For every time sound is proposed as a healing device or as a way to induce social cohesion, there are probably two occasions when it gets used as a weapon, in both our stories and our reality.

The idea of sonic weapons is a very old one. In the hundreds of thousands of years P.I.,
⁵²
our ancestors knew that sounds told them something was happening, usually something out of their control. The loud low rumbling of an earthquake or avalanche, the sudden snap of a twig and low growl of a predator in the dark, or the screaming of the wind during a hurricane all gave them warning of things powerful and to be avoided. And some ancestor of ours 17,000 years ago, long before sonic blasters were dreamed up for
Star Wars
, realized that if you took a flat piece of wood, put a hole in it, attached a long string to it and swung it over your head in a circle, it would create a low-pitched buzzing, roaring sound that changed as it got closer to or farther from the listener, a sound that people back then might have thought of as a helicopter had there been an accident with a time machine. This sonic weapon, the bullroarer, has been found in
archaeological sites on every continent but Antarctica, and indigenous Australians still use it in rituals to frighten away evil spirits. While the technology is simple, the sound it makes is loud and complex, based on the low-frequency oscillations of the wooden airfoil spinning on the string, and shifting up and down in frequency due to the Doppler effect as it approaches and retreats from a listener on its circular path. The sound of a big bullroarer is very much like that of a large animal vocalizing and breathing—hearing it at night around a fire certainly might have convinced listeners that some large, probably dangerous thing was invoked by this twirling sound source, and they could only hope that it was on their side against other things in the night. The bullroarer was thus one of the first uses of sound as a psychological weapon, even if it was aimed at some supernatural entity.

Sonic weapons have appeared in stories and real-world applications in every part of the world, from the ancient bullroarers to contemporary non-lethal weapons such as the long-range acoustic deterrent (LRAD), which has been used (or misused) against modern-day crowds. Their various applications have relied on technology from bits of bone or wood on a string to high-tech phase arrays of piezoelectric emitters. But unlike many other weapons, the stories and fear behind sonic weapons are often more effective than the weapons themselves. Their cultural pervasiveness tells more about our hidden psychological dependence and relationship to sound than does their actual effectiveness in the world.

The first class of sonic weapons that people in the West probably ever heard about were physical ones. According to a combination of biblical stories and archaeological research, around 1562 BC Joshua fought the Canaanites at the city of Jericho. The
battle was apparently quite fierce, ending with the walls of the city crashing down. According to the biblical version, a divinely inspired Joshua had his warriors simultaneously blow on their shofars—rams’ horns that can be played rather like a valveless trumpet—followed by a shout given by all the warriors at the same time. The massed common harmonic vibrations of the voices are supposed to have collapsed the walls, allowing Joshua and his people to do what touring bands always do: they destroyed the city completely, aside from Rahab the harlot, who apparently helped set up the gig.
⁵³

This story is one of the earliest about the use of acoustic weapons that could physically destroy something. It’s easy to understand why people might believe that a loud enough sound could knock a building down. A team of horses thunders into a village and pots get knocked off tables. An earthquake rumbles and a building collapses. A crack of thunder is heard close by and down the path a hut catches on fire. It’s a short mental association from hearing a sound and experiencing some destruction to believing that the sound in the air, which we perceive more easily than vibrations through the ground, is responsible for the damage. But while sound is based on transmission of energy by means of vibrating molecules, it takes a pretty specialized piece of equipment and a lot of power in a contained space to get a substantial physical impact from airborne sound.

So would it have been possible for the massed vibration of horns, voices, and silence, properly intermixed, to bring down the stone walls of a city? The short answer, when you talk to architectural engineers, archaeologists, and acousticians, is no. The rams’ horns in question in the story of Joshua can put out a very
loud sound (about 92 dB) with a fundamental frequency of about 400 Hz, with most of the harmonic power between 1,200 and 1,800 Hz, according to acoustician David Lubman. This puts the shofar at about the power and annoyance level of a male bullfrog. A human male voice can run from about 60 Hz to about 5,000 Hz, with most of the energy below 1,000 Hz, and a maximum loudness of about 100 dB when screaming at the top of your lungs. This makes us louder than a bullfrog, but not by much. Lubman actually carried out an analysis of the acoustic scenario of Jericho, presuming that there were 300 to 600 men all playing shofars with superhuman precision and then all shouting in unison. He found that this would still not generate even a millionth of the power needed to induce structurally damaging vibrations even in the stiffest, most brittle materials, even if they were right in front of them, not to mention the exquisite timing required to get the phase of the sounds aligned enough to induce resonance in structures of different masses and sizes. But it does make a good story that tells us more about our relationship to loud sounds than it adds to the historical record.

But sound that propagates through denser materials is a different story. Living about a hundred yards from an Amtrak line, I can attest to the destructive power that 700 tons of train cars moving at 30–40mph can transmit through the ground, and I have the cracks in my walls and ceilings to prove it. Sound traveling through a high-density medium moves much faster than it does in air, and so it attenuates more slowly. And if that vibration is in a closed structure, such as a metal-framed building, it’s not uncommon to have the structure resonate—vibrate sympathetically with the initial source of sound. If it’s allowed to continue, the resonance can build to the point that the structure fatigues and in theory could be damaged.

A story of this kind of destruction from modern times comes from the experiments of one of the most brilliant (and occasionally twisted) inventors of the modern era, Nicola Tesla. Born in 1856 in Smiljan, a village in what is now modern Croatia, Tesla emigrated to the United States and became known as the father of wireless transmission and alternating current. Among his fascinations was the idea of resonance, both electrical and acoustic. According to several biographies and innumerable conspiracy-theory websites, in 1898, Tesla was working with a small electromechanical oscillator that he attached to an iron pillar in his loft laboratory on East Houston Street in New York City. The story goes that as he let the oscillator run, the floors and space started resonating, causing small objects and furniture to start moving around the room. What happened next requires some skeptical inquiry: supposedly the resonance was propagating throughout the substrate of the building and then proceeded to start vibrating adjacent buildings and shops, blowing out windows and frightening people in nearby Little Italy and Chinatown; it did not stop until Tesla was alerted by the police pounding at his door. When asked if he had any idea what was causing the disruption, Tesla claimed (in one version) that he told them it was probably an earthquake, then showed them out and proceeded to destroy the oscillator with a sledgehammer, stopping the artificial earthquake.

When reporters arrived a bit later on, Tesla, with his typical tact and modesty, told them that he could have destroyed the Brooklyn Bridge in a few minutes if he’d wanted to. However, in a later article in the
New York World-Telegram
in 1935, Tesla gives a slightly different version of events, claiming it took place in “1897 or 1898.” “Suddenly,” he wrote, “all the heavy machinery in the place was flying around. I grabbed a hammer
and broke the machine. The building would have been down about our ears in another few minutes. Outside in the street there was pandemonium. The police and ambulances arrived. I told my assistants to say nothing. We told the police it must have been an earthquake. That’s all they ever knew about it.” While Tesla was an inventive genius with more than 700 patents to his name (including patents 514,169 and 517,900 for the oscillating engines supposedly at the heart of this story), he also was known to be rather expansive in his claims about how simple his devices were and how terrifying their results, such as his ability to “bring down the Empire State Building with 5 pounds of steam pressure” and one of his oscillators.