Thursday, February 28, 2013

Sound in Space

Over the past 20 years there have been some compelling experiments and discoveries made in the field of audio research in outer space by Dr. Neal London, professor at the Audio Research Institute at the University of Texas. Dr. London’s theory of sound in space, which he developed while an undergraduate at Texas A & M in the early 1990's, revealed that there is sound in space because space is not a true vacuum; it is actually a gaseous environment at extremely low pressure (on average about one hydrogen atom per cubic meter vs. trillions per cubic meter in the earth’s atmosphere). His theory held that because of the scarcity of hydrogen atoms in space that usually distort and impede sound movement in the earth’s atmosphere, sound would be hyper-activated; its volume intensified, its resolution greater than anything on earth. Sound would move, he suggested, in the medium of outer space in a hyper-activated slipstream that would exponentially heighten the experience of sound and add to its speed, purity, and clarity.

Dr. London surmised that the fidelity of sound in space would be as close as one can get to Alexander Graham Bell’s illusive “perfect sound” (a spectrally pure resonating hum that was created in the early Bell Labs in a contained hydrogen chamber). Bell’s experiments are the basis for the theory that the movement of sound depends on gas density. In other words, more gas, less sound density; less gas, more sound density. The conditions close to the Earth's surface allow sound waves to generate a strong pressure gradient that enables percussive shocks, but at the same time it ultimately impedes its forward flow, muting the sound over time. Dr. London believed that the lack of dense gases in outer space would allow sound to move in a slippery, more transmittable way that would reveal astounding results.

In 2003, Dr. London was invited by NASA to test his theories aboard the Space Shuttle Atlantis. The most interesting experiment Dr. London performed was recording the sound of his infant son crying and playing the recording from a speaker attached to the shuttle’s wing. He then placed a ribbon microphone (a highly sensitive microphone that is able to pick up sound vibrations from over a mile away) on the nose of the shuttle (a distance of approximately 30-feet). The sounds of his son crying were then broadcasted and recorded aboard the Space Shuttle Atlantis. The result astounded Dr. London. It sounded like “a stadium full of crying infants,” he said in an interview the following day. This was due to the "Doubler Effect" where sound waves are magnified and multiplied in space due to the lack of oxygen and a central cavity for sound to nestle in without a constrained receiving zone. Disproving the old movie tagline that "no one hears you scream in space." In fact, if you scream in space it would sound like a symphony of metallic screams in a hollow convention hall.

Dr. London’s shuttle experiment also addressed the effects of extreme cold on sound in space, where temperatures average around 350 degrees below zero. This extreme cold creates what is commonly referred to as “Void of Sound Effect,” or V.O.S. In extreme cold, sound doesn’t travel in crisp binary waves, but tends to be unstable, forming random sound clusters that bounce off matter unpredictably. In 1979, Dr. Louis Mitchell, a professor of audio research at Cambridge University, conducted a now famous experiment. He injected -200 degree Fahrenheit air into a metal container about the size of a popcorn bowl with a small electric bell inside. When he activated the bell, the sounds that emanated ricocheted around the room, until he deactivated the bell and released the cold air inside the container. This is precisely why it is difficult for children hear their parents shouting for them on a cold winter’s day, or why crowds at a ballgame sound muted in winter in comparison to a hot humid summer day when the crowd sounds can be deafening. Sound in extremely cold environments has a tendency to form in pools or clusters, confined by negative ions like a webbing or net. It moves as a mass that resembles more of a gelatinous sound mass, rather than a linear sound source. When sounds are projected through tinted smoke scientists can see the linearity of sound as it travels through warm air vs. the meandering blobs of sound we find in extremely cold air.

The best historical example of the instability of sound in extremely cold environments is to go back in time 113 years ago to Ernest Shackleton’s experiences during his explorations of Antarctica where he had firsthand experiences with sound “clusters.” The instability of sound sources bewildered Shackleton who frequently complained of being unable to hear one of his men shouting at that top of his lungs a mere 10 feet away. Sled dogs near their camp seemed to bark in silence but men more than a mile away could hear someone shouting or dogs barking as though they were a few feet away. This is because sound clusters are carried randomly to unsuspecting ears, regardless of where the sound was aimed or the distance from its source. In one account, Shackleton describes sound in extremely cold conditions:

“One of my men shouted to me from a glacial hill about a quarter mile in front of me but the sound of his voice came to me from behind. I turned to my rear to see who was there, but no one was there.” –E.S. April 15, 1901

Dr. London decided that the best way to reign in sound clusters was to give them direction with a propellant. Through the use of propulsion, sound in space would not only travel in a plasma blob in the cold, but could be pushed in such a way that it could arrive at its destination unimpeded by cold negative ions which hold sound back from delivering its full sound spectrum. The problem for Dr. London was how to direct sound in the extremely cold and airless environment of space. How could he make sound travel like a cannonball directly at the receiving mechanism in such a way that it would arrive at its intended target? His solution was a simple one: build a sound cannon fueled by Co2 cartridges. He used four feet of white PVC tube with a six-inch diameter and placed five C02 cartridges around its outer lip at the firing end. In the middle of the cartridges, he placed the speaker that broadcasted the sound of his son crying. At the instant the sound was played, the cartridges fired and propelled the sound to the intended target on the nose of the shuttle. The velocity of the sound cannon eliminated the sloppy randomness of blob diffusion and successfully propelled the sound of his son crying through outer space to its intended target.

What Dr. London discovered with his shuttle experiment was that sound in extremely cold conditions travels in plasma clusters, its spectrum divided into high and low sections that disperse the sound in uneven cycles. Dr. London unveiled a new sound template, revealing a level of clarity that even highly sophisticated microphones could barely register. The analogue sound meters that he used were overloaded immediately, their gauges not nearly sensitive enough to measure the new dimension of sound. Upon further investigation of the sounds through an aural spectrometer, Dr. London was amazed to discover that sounds projected to the microphones in space arrived in bunches that were perfect prisms. Each core sound held the stamp of what could only be described as perfect geometric scales. When he translated the sound data visually, the pattern it made looked much like the outline of a daisy drawn with a Spirograph. Architects have found parallels to these radical patterns in the work of Buckminster Fuller who anticipated the geometry of sound in his Geodesic Dome designs. In the 1940’s his work with the French composer Pierre Boulez anticipated the idea of sounds as physical structures when Boulez made tone cluster recordings that Fuller then translated (painstakingly and note for note) into architectural sound structures that became the basis for his geodesic domes.

In ideal conditions, the space between objects in outer space are essentially empty of all matter, meaning that sound in its pure plasma form corrupts the void in such a manner that it is accelerated by the lack of resistance. An apt analogy is to imagine sound being the size of your hand and space being a glove that is the size of Vermont: you'd never be able to touch all the ends of the finger holes simultaneously because the dimensions are simply incompatible. With no matter to dissipate the flow of sound, all that is left are the literally lighter parts of sound that are then hyper-activated. Therefore, sounds are not only louder in outer space; they are clearer and more robust than our ears can hear.

During his time on the shuttle, Dr. London made an interesting discovery regarding smells and sound. He did a preliminary study with astronauts who had done space walks outside of the shuttle where they were bombarded with high-energy vibrations of particles in outer space. These particles can both accelerate and impede the flow of sound and in many instances create a distinct odor on the astronauts coming back in the shuttle after a spacewalks. Dr. London, and many of the astronauts who have walked in space, have reported smelling cooked meat, and their suits smelling of freshly welded metal when arriving back in the shuttle. This is the result of the high-energy particles and the considerable amount of debris outside the earth’s atmosphere (old satellite parts no bigger than a peanut tend to cluster together in zero gravity called by astronauts "nut clusters") that create enormous heat and friction on anything they come in contact with (in this instance, the astronaut’s suits). These clusters, when sound passes through them, distort the flow of sound and present enormous obstacles--literally and figuratively--in sound projection in outer space.

Dr. London’s later studies of dust, (dust is quite prevalent in space) revealed interesting swirl patterns in zero gravity. Dr. London referred to this phenomenon as “The Swirl Effect.” It is equivalent to a multi-track recording. In outer space this phenomena is compounded by the lack of oxygen where sound is not only directionless, but it replicates itself and intertwines repeatedly like a tightly wound rope, thus adding not only to its density, but also its clarity and volume. When sounds from outer space are played through a computer program called “PRISM” (developed at MIT during the cold war to analyze sound for Dolby Labs, the same audio lab currently used for mastering sound by virtually all contemporary films) Dolby Labs found that the spectral analysis captured was perfect. In other words, the geometric conversion of sound into geometrically quantifiable information yielded the most perfectly precise representation of sound ever captured by spectral analysis. Every angle in the geometric representation of sound was as close to perfection as had ever been captured. Remarkably, we have no modern utensils that allow us to see any imperfections in the geometry of this sound from outer space.

What does all this mean for the future of sound on earth? For one, it allows developers of headphones, recording engineers and the like to explore spectrums of sound previously only theorized about. Already there are practical applications in live concert hall settings where musicians use outdoor spectral perfection amplifiers as a way to multiply sound and add a richness and depth to brittle, one-dimensional sound sources. On an even more radical level, sound in outer space is being experimented with as a mode of transport, sending spaceships deep into space by propelling them with their own sound. Dr. London has even suggested that here on earth, in only a few decades, vehicles will no longer use fuel, but will be propelled by the very sounds they make. The future looks very noisy indeed.

2 Comments:

Anonymous Anonymous said...

Brilliant!

8:01 PM  
Anonymous Anonymous said...

ditto.

10:15 AM  

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