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Mains Hum.

At the age of 16, I read of the earth-battery experiments of Scottish inventor Alexander Bain, who had generated a permanent voltage by use of buried metal plates that could power the prime mover of an electric clock. (1) Inspired by the idea of permanent free power, I built an earth battery constructed of alternating plates of lead and zinc buried in the topsoil. This created a measurable but small permanent current of slightly under one volt. At the time, I believed this voltage to be entirely the result of chemical-electric effects similar to that achieved by the insertion of electrodes into a lemon or a potato. (2)

Earth batteries were developed in the 1840s and were used to power the communications between telegraph stations. Many patents were granted for variations on the same concept, where plates of two different metals are buried in the soil, which acts as an electrolyte similar to a lead acid battery. Lord Kelvin developed a sea battery and discovered that the resulting voltage was not due to a chemical process as the orientation of the plates would alter the amount of current measured, something that would not occur with the plates of a chemical battery. (3) The discovery of an electrical potential between the stations of the telegraph, along with the voltage differentials demonstrated by the sea battery, suggested the existence of naturally occurring electrical currents flowing in the earth. These were named telluric currents after the Latin tellus: the earth. (4)

The fundamental causes of telluric currents have been understood since the late twentieth century. In their study of the interactions between telluric currents and man-made electrical systems, Lois Lanzerotti and Giovanni Gregori explain that telluric currents
   are produced either through electromagnetic induction by the
   time-varying, external-origin geomagnetic field, or, whenever a
   conducting body (such as seawater) moves (because of tides or other
   reason) across the Earth's permanent magnetic field. (5)

They are also fed by and have a direct relation to lightning from thunderstorms. (6) Telluric currents encircle the globe and are used by geologists and geophysicists to determine the nature of underlying rock formations. Geophysicists have published charts illustrating their global distribution. (7) The currents are of extremely low frequency and voltage and have collective regular periodic fluctuations; they are diurnal and tend to follow the direction of the sun. Perturbations in telluric currents occur simultaneously over the entire globe as measured by global networks of instruments.


Bonification is the interpretation of information through sound. One of the first sonifications was the Geiger counter, which creates sound in response to the presence and intensity of radiation. Bonification can be a direct and immediate conduit to an intuitive understanding of the nature of the phenomenon under observation. My interest lies in the direct sonification of the signals themselves, or at least in employing a process that uses as little mediation as possible. Preferably I'd like to develop a technique that preserves naturally occurring informational patterns so that the observer can perceive the nature of the phenomena directly and in real time. The aesthetics of such raw sounds (often understood as visualisations rather than sonifications) can be relatively unfamiliar and inaccessible, but they do represent actual phenomena. The sounds we hear are shaped by external information and are a faithful portrayal of the unseen. Through sonification a window is opened to an understanding of something that otherwise would remain hidden.

Paul Vickers divides sonification into two forms that show how data can be mapped to sound:
   ... direct mappings impose a one to one relationship between data
   items and sonic events (possibly involving some scaling and
   quantisation) whilst metaphoric or analogic mappings impose
   interpretive filters or mapping functions to the data before it is
   rendered. (8)

Vickers notionalises this relationship as a continuum between what he terms 'Ars Informatica' and 'Ars Electronica.' At the Ars Informatica end of the continuum sonification is a direct mapping of the data with little or no artistic intent, while at the Ars Electronica end sonification exists as pure art form with little or no attempt to communicate ideas from the real world. (9) It is possible however that artworks can directly sonify data and inhabit a space in between Ars Informatica and Ars Electronica. The following artworks can be considered as works that occupy both ends of this continuum simultaneously.

Christina Kubisch's Electrical Walks (2003) involve the participant wearing specially designed magnetic headphones with built-in coils that respond to electrical fields and produce sound in the wearer's ears. (10) The artist supplies participants with headphones and a map showing the locations of the fields to visit. In a short journey, the participant can listen to the otherwise unseen fields of light systems, transformers, anti-theft security devices, surveillance cameras, cell phones, computers, elevators, streetcar cables, antennae, navigation systems, automated teller machines, neon advertising, and electric devices. Kubisch says,
   The perception of everyday reality changes when one listens to the
   electrical fields; what is accustomed appears in a different
   context. Nothing looks the way it sounds. And nothing sounds the
   way it looks. (11)

Kubisch makes a point of not labelling this ecology as good or bad:
   I could tell everyone that I think it's bad. But that wouldn't be
   an experience. It would just be didactic. On the other hand, this
   stuff is very fascinating as well. (12)

Kubisch's work reveals the unseen aspects of a local environment and transforms what might be regarded as electromagnetic pollution into a source of illuminating information. It is a directmapping sonification revealing an electromagnetic ecology emanating from our technology, and yet the work is clearly art; both Ars Informatica and Ars Electronica.

Australian cross-disciplinary artist Joyce Hinterding's gallery work, Aeriology (1995), is an extensive antenna array directly sonifying local airborne VLF phenomena.
   Made from over twenty kilometres of copper wire that has been
   wrapped around the gallery's architecture, Aeriology transforms the
   space into a beautiful walk-in radio antenna. Through sympathetic
   amplification the harmonising coils of this installation reveal
   otherwise unheard activity turning the ethereal into audio. (13)

Hinterding describes Aeriology as a machine for a techne of the invisible. (14) The work reveals the unseen signals of the air, both man-made and naturally occurring. Hinterding also found that electromagnetic pollution from the city's electrical distribution system pervaded the local electromagnetic ecology:
   ... if you listen to the VLF antenna in the middle of a city, you
   really cannot hear much except for a big 50 hertz hum.... So the
   strongest element in the local city electromagnetic landscape at
   the VLF end of the spectrum is the sound radiating off our
   electrical system. But if you go somewhere away from electrical
   powerlines you will hear a whole range of other sounds. (15)

Aeriology reveals another unseen electromagnetic ecology using simple technology to achieve a directly mapped sonification that exists as both art and science.

Other cross-disciplinary artworks drawing on science as a source for sonification have explored naturally occurring signals. Artists have used the phenomena of space, such as Radioqualia's Radio Astronomy (2004); of protein data in John Dunn and Mary Anne Clark's Life Music (1998); and of seismic data, as in Marty Quinn's Seismic Sonata (2001). (16) It is true that the human sensory apparatus of perception struggles to directly perceive many phenomena. Illustrating the unseeable invariably involves format- or state-shifting, shifting the temporal scale, or otherwise reinterpreting the data. If the artistic intent of the work is to illustrate the unseen, as little mediation as possible will most effectively meet that goal. In an attempt to meet this challenge, my work Mains Hum (2009) drew on the signals of the ground for its directly mapped sonification.



Almost 30 years after my earth battery experiment, I thought to revisit the idea. I went out into the backyard and inserted two copper rods into the ground. When I measured these with a voltmeter I was amazed to discover about 0.3 volts just pouring out of the ground. This could not be a chemical battery effect as both electrodes were of the same metal. I moved these makeshift electrodes around a variety of places in the backyard and found the voltage was present at about the same strength everywhere. I connected the electrodes to a pre-amplifier, in turn connected to an amplified loudspeaker in order to hear this ubiquitous signal. The resulting sound was a rich textured hum comprising a 50 Hz bass tone with layers of harmonics at intervals based on that frequency. The hum was not fully constant; various artefacts could be heard; there were sudden alterations in the frequency distribution, clicks and spurious noises. Inspired, I hauled out a 300 watt PA system with mains cable and really gave it voice. This constituted the first iteration of my Mains Hum installation, although the neighbours probably didn't recognise it as such.


I realised that the signal I was finding in my backyard must have been coming from the electrical mains as it was a familiar frequency, being of the same pitch as a short circuit or unearthed audio signal. Furthermore, the sound could be altered by turning the oven on and off despite the ground electrodes being more than ten meters away.

I then took the pre-amplifier, electrode apparatus and my laptop out into the field to see if I could find and record this signal in other locations. The further away from town (and my own backyard) I got, the more the mains hum signal level dropped away. I needed a much more advanced instrument to be able to hear it than my simple handmade pre-amplifier, which only amplified the signal by 40-50 times. I could hear the same signal faintly about 5 kilometres from my backyard on a nearby mountain, about 7 kilometres away in the forest and, just barely, 12 kilometres away on the beach. Distance from the city had a clear impact on the signal strength.

So where does all this electricity come from, and, as it pervades a large amount of human and animal habitat, how does it affect the organisms living in or on the ground? The man-made electrical current that produces this mains hum is very pervasive; it predominates over the more subtle naturally occurring telluric currents many kilometres from a major town, city, or large-scale electrical installation such as an electric train system, power station or certain type of factory. (17) Mains voltage pollution has been detected emanating from electric trains at distances ranging from a 20km distance in Montreal to as far as 115km from the Paris-Toulouse electric railway. (18) Dahlberg suggests that the proliferation of electrical generation and distribution systems is responsible for radically altering the nature of the ground currents flowing in the uppermost layer of the earth. (19)
   The neutral wire in the entire system was wired to the earth
   through the ground rods and other connections in the earth. This
   connection has produced an electrical distribution system, which
   uses the earth in parallel with the neutral wire as the return path
   for the electric current. (20)

To increase safety from electrical shocks, distribution companies increase the number of earthing points, often using water pipes and earthing rods that feed current into the ground. Dahlberg continues:
   The present multi grounded system has the disturbing effect of
   placing every living organism in contact with one terminal (the
   neutral wire) of the entire electrical distribution system ... As
   human beings, we literally stand on one terminal of the electrical
   system with no way of escaping that state. The consequences of this
   continual contact are numerous. An assumption has been made that
   the multi grounded system places living organisms on an
   equipotential plane, the earth connected to the neutral of the
   system. An additional assumption follows, that an equipotential
   plane is an electrically safe place to be. (21)

Stray voltage is the extraneous voltage that is generated on grounded surfaces when current flows through the resistance of a ground path. (22) The term is used to refer to small electric shocks coming from inadequate wiring of a localised electrical system. (23) Stray voltage in dairy barns, thought to be from frequent small electric shocks, has long been known to cause problems for livestock. (24) Dahlberg describes these effects "includ[ing] a sudden onset of a number of bacterial diseases as well as a gradual deterioration of the muscle and skeletal structure of the body." (25) The cows are thought to receive small shocks when contacting the metal of the barn. Dahlberg suggests that constant exposure to electromagnetic ground currents from natural and man-made sources are more likely responsible.

When researching the possible effects on organisms of exposure to these artificial ground currents, I quickly realised that there is little science being done in this field. There are many organisms that use or are affected by the earth's magnetic fields, however, and electrical currents produce magnetic fields including our telluric ones. Ground currents have been shown to cause induced currents in trees. (26) Magnetic fields are known to be used for navigation by birds, but are also used by ground-dwelling aquatic bacteria. (27) Little is known about the effect of these types of fields in humans, although enhanced DNA synthesis has been reported for human fibroblasts exposed to magnetic field fluctuations with frequencies and amplitudes similar to many geomagnetic occurrences. (28) Liboff points to a possible mutagenic effect:
   The range of magnetic field amplitudes tested encompass the
   geomagnetic field, suggesting the possibility of mutagenic
   interactions directly arising from short-term changes in the
   earth's field. (29)

Another study shows an interaction between magnetic fields and biological systems within similar ranges of magnetic field strength.
   Cell studies show that magnetic fields at some frequencies,
   amplitudes, and wave forms interact with biological systems ...
   Cellular and physiologic studies thus suggest effects that may be
   related to cell multiplication and tumor promotion. (30)

What can be seen from the above is that the electricity in the ground is coming from our system of electrical distribution via a large number of grounding points acting as conduits channelling voltage into the ground. The ground acts as part of the electrical circuit. These man-made ground currents greatly dominate an electromagnetic ecology that once would have consisted of not much more that the subtle and varied naturally occurring telluric currents. While this collection of results and responses can hardly be considered scientific proof of immanent danger, it equally cannot be said that these ground currents can be considered entirely benign. It may be appropriate to refer to these artificial ground currents as electromagnetic pollution. It seems that an artistic response to this collection of data is also appropriate. My Mains Hum sonification directly maps information about the presence of this electricity and provides an opportunity to apprehend aspects of its nature. The work exists simultaneously as both Ars Electronica and Ars Informatica.

MAINS HUM (2009)

These findings formed the basis for my recent performative sonification work Mains Hum (2009). (31) For this, I constructed a set of large copper electrodes and inserted them into the ground to pick up the electrical signals of the site. I fed the signal into a pre-amplifier circuit and then into an audio mixer and P.A. system. I then let the machine I had assembled give voice to the ground's electromagnetic environment.


What was surprising was the amount of texture and variance of sound in the hum. The sound contained spontaneous artefacts, sudden pulses, clicks and slight pitch and timbre changes. The cause of these perturbations most likely corresponded to changes in the city's electrical demand or the change in electricity use of nearby buildings as various machines or processes were activated or deactivated. It is also possible that some interaction between the man-made electrical currents and the ground's natural electromagnetic ecology may have been responsible for some of these variations. The work served to draw attention to the existence of this electricity in the ground and suggested an awareness of it as electrical pollution. The signal exists as a voltage in the ground and, in order to make it audible, the signal shifted states from an unseen voltage to acoustic sound waves. The sound when amplified to a moderate to loud volume can be challenging for the visitor to the space; it can be perceived as some type of malfunction. Many in the audience of Mains Hum assumed that the sound they heard was produced by direct amplification of sound in the earth, as if from a buried microphone. In order to have the work read, it is necessary to make available the requisite information. The sonification itself cannot give the full range of information for interpretation and source simultaneously; listeners need both Ars Informatica and Ars Electronica in order for the work to make sense. This type of cross-disciplinary sonification, which involves both Ars Electronica and Ars Informatica together, can be an effective technique, bringing attention to the existence of unseeable electrical processes and raising questions around what human activity may be doing to natural electromagnetic ecologies.

In the early twenty-first century telluric currents have not yet disappeared, but our ability to perceive them is becoming weaker. Overtaken by a different disciplinary formation of electronic pollution, the telluric current deserves to be heard. A future project may be to design and construct another installation apparatus that can eliminate the mains hum pollution to reveal and sonify the naturally occurring telluric currents, revealing another electromagnetic ecology, that of the Earth itself.

(1) Wikipedia, Bain_(inventor) [accessed 6 Oct 2010].

(2) Wikipedia, battery [accessed 6 Oct 2010].

(3) Free Patents Online, "Method and Apparatus for Generating Electricity: United States Patent4153757," [accessed 9 Oct 2010].

(4) Powerpedia, "Earth Battery," index.php/PowerPedia:Earth_battery [accessed 9 Oct 2010].

(5) Lois J. Lanzerotti and Giovanni P. Gregori, "Telluric Currents: The Natural Environment and Interactions with Man-made Systems," in The Earth's Electrical Environment, ed. Philip Krider and Raymond G. Roble (Washington: National Academy Press, 1986), 232.

(6) Lanzerotti and Gregori, "Telluric currents," 234.

(7) Lanzerotti and Gregori, "Telluric currents," 234.

(8) Paul Vickers, "Ars Informatica--Ars Electronica: Improving Sonification Aesthetics," Interaction Design Centre, Limerick, Ireland (2005), aesthetics/WSpapers/VickersSonificationAesthetics. pdf [accessed 8 Oct 2010].

(9) Vickers, "Ars Informatica--Ars Electronica." (10) Christoph Cox, "Invisible Cities: An Interview with Christina Kubisch," Cabinet 21 (Electricity, Spring 2006), Interview.pdf [accessed 18 Oct 2010]

(11) Kubisch in Cox, "Invisible Cities." (12) Kubisch in Cox, "Invisible Cities." (13) Aeron Tozier, "Aeriology, "Reg Vardy Gallery (2010), Joyce%20Hinterding/index.html [accessed 7 Oct 2010].

(14) Joyce Hinterding, "Aeriology," SunValleyResearch (2009), http://www.sunvalleyresearch.ne1/?series=19 [accessed 9 Oct 2010].

(15) Josephine Bosma, "Interview with Joyce Hinterding," Soundsite: The Online Journal Of Sound Theory, Philosophy of Sound and Sound Art (1998), http:// [accessed 9 Oct 2010].

(16) Honor Harger and Adam Hyde, Radioqualia (2004), sonification of extraterrestrial phenomena, sound installation and radio broadcast, exhibited at ISEA (Inter-Society for the Electronic Arts), URSA observatory, Kaivopuisto Park, Helsinki, Finland, [accessed 28 Oct 2010]; John Dunn and Mary Anne Clark, Life Music (1998), sonification of proteins, audio CD, exhibited at Algorithmic Arts, Fort Worth, Texas, U.S.A., http://www. [accessed 28 Oct. 2010]; Marty Quinn, The Seismic Sonata (2001), sonification of the 1994 Northridge, California, Earthquake. CD produced in conjunction with the IRIS Consortium, Washington, DC., http://www.quinnarts. com/srl/seismic.html [accessed 28 Oct. 2010]

(17) M. N. Berdichevskiy, "Electrical Prospecting with the Telluric Current Method," Quarterly of the Colorado School of Mines 60, no.1 (Jan 1965): 124.

(18) Lanzerotti and Gregori, "Telluric currents," 246.

(19) Duane A. Dahlberg, "Ground Currents: An Important Factor in Electromagnetic Exposure," SNCMFG The Stray Voltage Mitigators (1995), http://www.sncmfg. com/telecom/stray_voltage/dahlberg.html [accessed 8 Oct 2010].

(20) Dahlberg, "Ground Currents." (21) Dahlberg, "Ground Currents." (22) John Bass, "What Causes Stray Voltage?" Bass Associates Ltd. (1995), http://www.bassengineering. com/SV_Cause.htm [accessed 8 Oct 2010].

(23) Douglas J. Reinemann, "What do we Know About Stray Voltage?" University of Wisconsin, Madison (2003), What_do_we_know_about_Stray_Voltage.pdf [accessed 8 Oct 2010].

(24) R. D. Applemana and R. J. Gustafsona, "Source of Stray Voltage and Effect on Cow Health and Performance," in Journal of Dairy Science 68, no 6 (June 1985): 155467. Departments of Animal Science and Agricultural Engineering, University of Minnesota, http://www. [accessed 8 Oct 2010].

(25) Dahlberg, "Ground Currents." (26) A. C. Fraser-Smith, "ULF Tree Potentials and Geomagnetic Pulsations," Nature 271, no. 5646 (Feb. 1978): 641-2, journal/v271/n5646/abs/271641a0.html [accessed 9 Oct 2010].

(27) R. P. Blakemore, "Magnetoactive Bacteria," Science 190 (1975): 377-9, content/abstract/sci;190/4212/377 [accessed 9 Oct 2010].

(28) Lanzerotti and Gregori, "Telluric currents," 249.

(29) A. R. Liboff, T. Williams Jr, D. M. Strong, and R. Wistar Jr., "Time-varying Magnetic Fields: Effect on DNA synthesis," Science 223, no. 4638 (Feb. 1984): 818-20, abstract/223/4638/818 [accessed 18 Oct 2010].

(30) B. Holmberg, "Magnetic Fields and Cancer: Animal and Cellular Evidence--An Overview," Department of Toxicology, National Institute of Occupational Health, Solna, Sweden (1995), http://www.ncbi.nlm.nih. gov/pmc/articles/PMC1518854/ [accessed 18 Oct 2010].

(31) Pete Gorman, "Mains Hum" (2009), online documentation, html.
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Author:Gorman, Pete
Publication:Junctures: The Journal for Thematic Dialogue
Article Type:Report
Geographic Code:1USA
Date:Dec 1, 2010
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