Sferics

Sferics is one of Lucier’s most elegant and simple works. It is just a recording. Other versions of Sferics could be produced, and many science and radio hobbyists make similar recordings without ever having heard of Alvin Lucier. The phenomenon at the heart of Sferics existed long before they were ever able to be detected and recorded. Listening to this form of natural radio requires going down to the Very Low Frequency (VLF) portion of the radio spectrum.

The title of Lucier’s work refers to broadband electromagnetic impulses that occur as a result of natural atmospheric lightning discharges and are able to be picked up as natural radiofrequency emissions. Listening to these atmospherics dates all the way back to Thomas Watson, assistant of Alexander Graham Bell, as mentioned at the beginning of this book. He picked them up on the long telegraph lines which acted as VLF antennas. Since his time telegraph operators and radio hobbyists and technicians have heard these sounds coming in over their equipment. For some chasing after these sferics has become a hobby in itself.

The VLF band ranges from about 3 kHz to 30 kHz and the wavelengths at this frequency are huge. Most commercial ham radio transceivers tend to only go as low as 160 meters which translates to between 1.8 and 2 MHz in frequency. A VLF wave at 3 kHz is by comparison a length of 100 kilometers. The VLF range includes a portion of the spectrum that is in the range of human hearing, from 20 Hz to 20 kHz. Yet since the sferics are electromagnetic waves rather than sound waves a person needs radio ears to listen to them: i.e., an antenna and receiver.

On average lightning bolts strike about forty-four times a second, adding up to around 1.4 billion flashes a year. It’s a good thing the weather acts as a variable distribution system of these strikes, though some places get hit more than others. The discharge of all this electricity means there are a lot of electromagnetic emissions from these strikes going straight into the VLF band where they can be listened to with the right equipment. Because these wavelengths are so long, you could be in California listening to a thunderstorm in Italy or India, or in Maine listening to sferics caused by storms in Australia.

The sound of sferics is kind of soothing and reminds me of the crackle of old vinyl that has been unearthed from a dusty vault in a thriftstores basement. There are lots of pops and lots of hiss. As these are natural sounds picked up with the new extensions to our nervous system made available by telecommunications listening to sferics has the same kind of soothing effect as listening to a field recording of an ocean, or stream meandering through lonely woods. But for a long time, listeners, hobbyists and scientists didn’t really know what these emissions were caused by. During the scientific research activities surrounding the International Geophysical Year (IGY) overlapping 1957-58 their presence and source was verified.

The IGY yearlong event was an international scientific project that managed to receive backing from sixty-seven countries in the East and West despite the ongoing tensions of the Cold War. The focus of the projects was on earth science. Scientists looked into phenomena surrounding the aurora borealis, geomagnetism, ionospheric physics, meteorology, oceanography, seismology, and solar activity. This was an auspicious area of study for the scientists, as the timing of the IGY coincided with the peak of solar cycle 19. When a solar cycle is at its peak, the ionosphere is highly charged by the sun making radio communications easier, and producing more occurrences of aurora, among other natural wonders.

One of the researchers was a man by the name of Morgan G. Millett, and his recordings would go on to have a direct influence on Alvin Lucier. Millet was an astrophysicist who had established one of the first programs to use the fresh discoveries occurring in the VLF band as a way to investigate the properties of space plasma around the earth, in the region now known as the upper ionosphere and magnetosphere. His inquiries into this area allowed for deep gains of knowledge in a new area of study before space-crafts began making direct observations of this area.

Millet was also a ham radio operator with the call sign W1HDA. He had been interested in radio since he was a teenager, and throughout his career found ways to use his inclination and knack to research propagation. Throughout the 1940s and early 50s Millet and his colleagues conducted radar experiments near his home in Hanover, New Hampshire. The purpose of these studies was to observe two modes of propagation that magnetoionic theories had predicted would occur when radio waves entered the atmosphere.

During the IGY he chaired the US National Committee's Panel on Ionospheric Research of the National Research Council. In this capacity he oversaw the radio studies being conducted all around the earth. As part of that work he joined the re-supply mission to the US Antarctic station on the Weddell Sea in early 1958 as the senior scientific representative. For his own specific research he maintained a series of far-flung stations spread across the Americas. It was from these that he made a number of recordings of natural radio signals.

Lucier later heard these at Brandeis. The composer writes, “My interest in sferics goes back to 1967, when I discovered in the Brandeis University Library a disc recording of ionospheric sounds by astrophysicist Millett Morgan of Dartmouth College. I experimented with this material, processing it in various ways -- filtering, narrow band amplifying and phase-shifting -- but I was unhappy with the idea of altering natural sounds and uneasy about using someone else's material for my own purposes.”

Millets recordings were made at a network of receiving stations and he interpreted the audio data he collected to obtain some of the earliest measurements of free electron density in the thousands of kilometers above earth. A colorful vocabulary was built up to describe the sounds heard in the VLF portion of the spectrum. Sferics that traveled over 2,000 kilometers often shifted their tone and came to be called tweeks; the frequency would become offset as it traveled in distance, cutting off some of the sound and making it sound higher in the treble range. Whistlers were another phenomenon heard on the air. They occurred when a lightning strike propagated out of the ionosphere and into the magnetosphere, along geomagnetic lines of force. The sound of a whistler is one of a descending tone, like a whistle fading into the background, hence its name. It is similar to the tweek, but elongated due to it stretching out away from the surface followed by a return to the Earth’s magnetic field.

Dawn chorus is another atmospheric effect some lucky eavesdroppers in the VLF range may be able to pick up from time to time. It is an electromagnetic effect that may be picked up locally at dawn. The cause of this is thought to be generated from energetic electrons being injected into the inner magnetosphere, something that occurs more frequently during magnetic storms. These electrons interact with the normal ambient background noise heard in the VLF band to create a sound that is actually similar to that of birdsong in the morning. This sound is likely to be heard when aurorae are active when it is dubbed auroral chorus. Millets experimental work in recording these phenomena created a foundation to study such things as how the earth and its magnetic field interact with the solar wind.

Listening to Millet’s recordings wasn’t enough for Lucier. “I wanted to have the experience of listening to these sounds in real time and collecting them for myself. When Pauline Oliveros invited me to visit the music department at the University of California at San Diego a year later, I proposed a whistler recording project. Despite two weeks of extending antenna wire across most of the La Jolla landscape and wrestling with homemade battery-operated radio receivers, Pauline and I had nothing to show for our efforts. . . .” The idea was shelved for over a decade.

In 1981 Lucier tried again. He got a hold of some better equipment and was able to go out to a location in Church Park, Colorado, on August 27th, 1981. For the Colorado recording he collected material continuously from midnight to dawn with a pair of homemade antennas and a stereo cassette tape recorder. He repositioned the antennas at regular intervals to explore the directivity of the propagated signals and to shift the stereo field. This was all done at Church Park, August 27th, 1981.

It was in the early 80s that Millet continued his own radio investigations. He built a network of radar observing stations to study gravity waves that propagate to lower latitudes of Earth from the arctic region. These gravity waves appear as propagating undulations in the lower layers of the ionosphere.

Lucier wasn’t the only musician to be interested in this phenomenon. Electronic music producer Jack Dangers explored these sounds under his moniker as Meat Beat Manifesto on a song called The Tweek from the album Actual Sounds & Voices. Pink Floyd used dawn chorus on the opening track of their 1994 album the Division Bell. VLF enthusiast Stephen P. McGreevy has been tracking these sounds for some time, and has collected a lot of recordings and been releasing them on CD and the internet via archive.org. At the time of this writing he has made eight albums of such recordings.

On the communications side of things the VLF band’s interesting properties have been exploited for use in submarine communication. VLF waves can penetrate sea water to some degree, whereas most other radio waves are reflected off the water. This has allowed for low-bitrate communications across the VLF band by the worlds militaries. Some hams have also taken up experimenting with communication across VLF, learning more about its unique propagation in doing so.