Research - Aelectrosonic Truss 2025, site specific sonic sculpture The Center for Land Use Interpretation, Desert Research Station, Hinkley, CA
Exhibition run: Jan 11 – Mar 15, 2025
Steve Badgett & Deborah Stratman
NATURAL RADIO KEY – WHAT AM I HEARING?
Most natural radio signals are generated by lightning strikes which occur globally between 100 and 200 times a second.
Spherics (aka Statics) are radio signals radiated by lightning and are extremely common. They are electromagnetic emissions with a broad spectrum, though most of their energy is concentrated within the audio frequencies, which coincide with the VLF band. Spherics sound like the noise made by dust on an old vinyl record, or dissolving Pop Rocks your mouth.
Tweeks are a distortion the spheric suffers when the signal bounces off and reflects back from the highest layer of the ionosphere. As the spheric travels, it experiences dispersion, where higher frequencies arrive before lower. They are received only at night and more often in the winter. Tweeks sound like a twittering. You hear the spheric and at the same time single or multiple “ciuuups,” lasting about a tenth of a second.
Buzzers are signals produced by the current flowing between clouds and the ground, induced by the potential difference. When this value is high enough, small channels are created in the air where current flows and creates electrical noise. They can last from minutes to hours and are best heard at high elevation or when clouds are low and dense. Unlike spherics and tweeks, they are local signals and can only be heard within a few kilometers of the generating phenomena. Buzzers sound like bees trapped in a small space. They are usually composed of a time varying base frequency and some harmonics of decreasing amplitude as the frequency rises.
Whistlers are generated primarily by full-spectrum electromagnetic bursts of lightning. When these signals bounce between the earth and the ionosphere, they sometimes catch a ride into outer space on magneto-ionic flux lines before arching over the equator and descending back to earth in the opposite hemisphere. The way the frequencies from the initial burst of lightning are spread out into a glissando is similar to how light is refracted and spread out into a rainbow. Whistlers sound like whistles, a “fiiiiuuuuuu” that descends in frequency. They can last from half a second to several seconds.
Auroral Chorus originates from the interaction of solar wind with our magnetosphere. Storms occurring on the sun's surface release energy towards earth as radio waves, X-rays (solar flux) and particle bursts (coronal mass ejections and the solar wind). When this energy hits the magnetosphere, it creates the luminous physical effect of aurora. VLF signals generated by the aurora can be listened to at any time but are strongest at local sunrise. Auroral chorus sounds like a flock of vocalizing birds or coyotes singing. They are comprised of musical whistles, often simultaneous and at multiple frequencies.
ANTHROPIC VLF
Many VLF transmission sources are man-made; some intentionally, others collaterally.
The most ubiquitous is the 60Hz hum of the power grid. Other collateral transmissions emanate from electrical devices, including power tools, hair dryers, induction cookers, headlamps, televisions, dimmer switches, computers, cell phones and security systems.
Intentional VLF signals are those generated by entities requiring global coverage, subsurface and/or seawater-penetrating properties. They include time signals, industrial mining operations, submerged submarine communications and transmissions used by national command authorities in wartime. In the US, coded submarine broadcasts operate on VLF frequencies from 14 to 60 kHz, and are transmitted from Minimum Shift Keyed high-powered sites including stations NLK (Jim Creek) in Seattle, Washington (24.8 kHz); NML in LaMoure, North Dakota (on 25.2 kHz); NPM at Lualualei, Hawaii (on 21.4 kHz and 23.4 kHz); NAU at Aguada, Puerto Rico (on 40.75 kHz), NPG at Dixon, California (on 55.5 kHz), and NAA at Cutler, Maine (on 17.8 kHz and 24 kHz).
Dawn Chorus from Steven McGreevy
Growler Whistlers Spherics Tweeks from Steven McGreevy
