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the instrument sounds & pictures

Magnetic Focus
ELF receivers, wire coil antennas, and radiative devices
by Absolute Value of Noise © 2006.

"Magnetic Focus is an instrument that I use in performance. It is based on ELF (extremely low frequency) technology .. I use a series of wire coil antennas, and various devices that create radiation patterns."

ELF or extremely low frequency radiation is electro-magnetic radiation that corresponds to the audio frequencies that can be heard by the human ear and the ultrasonic frequncies that are just above human hearing. This translates into magnetic fields that oscillate between 20 Hz and 80,000 Hz. These frequencies of electromagnetic radiation surround us constantly, but we have no direct way to sense them. They can be translated into sound through the use of an ELF receiver and speakers. Unlike the radio waves that we use for broadcast (AM, FM, cell-phones, etc..), ELF signals have a significant difference in wavelength from their lowest frequency to their highest frequency. ELF receivers can be as simple as a wire coil plugged into a microphone preamplifier, or consist of more complicated broad-band receiver stages.

In performance, I work with a magnetic field antenna and receiver. The antenna is a loop with a 26 inch circumference. It is designed so that it can be turned and swivelled in all directions. This type of antenna and movement, allows one to pull focused (directional) signals out of the environment. "Natural" ELF radiation is caused by phenomenon such as solar-flares, the aurora borealis, and lightning storms. In populated areas, this natural radiation is mixed with and often obliterated by the noise of power-lines, transformers, and fold-down from higher frequency transmitters (radio transmitters, computers, monitors, cell phones, anything electronic). By passing the output of the ELF receiver through various filters, it's possible to remove the more annoying man-made noises (in particular power-line hum) and focus on the natural sounds mixed with more subtle frequency fold-down effects from wireless equipment and other electronic sources. In a particular performance space, the ELF fields can be mapped by the performer and turned into a composition of motion and tuning - the act of turning the antenna and moving it through space turns it into an odd musical instrument that pulls hidden sounds from the ether.



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