VLF (Very Low Frequency) is a range of frequencies below 22kHz. These frequencies also carry electromagnetic activity. VLF recording, done far from cities (no electricity), is a way to catch sound from stratospheric activity — sometimes described as radio astronomy.

VLF recorded in the Mediterranean Sea — 2016

Through a week-long journey, recorded at night in the middle of the sea: an electromagnetic storm transmitting from the sky.

VLF recorded around Frostrup / Denmark — 2015

VLF recorded in Moulin Foulon — Cugand, FR — 2013

VLF recorded with a BBB4 receiver — Swedish Lapland, winter 2009 (by Brice Jeannin)

On the first recordings you can hear a soft chorus in the background, recorded between 7 and 8 AM on 25th of March, about 15km north of Hemavan — sometimes sounding like birds singing at dawn or faraway whistles, possibly related to an aurora borealis. Other recordings capture discrete emissions — “risers” and “combinations” — due to the interaction of solar wind and magnetosphere, recorded on the frozen Tärnaby Lake between 7 and 8 AM on 27th of March.

References: Radio Nature by Renato Romero (vlf.it), BBB4 Receiver schematic (auroralchorus.com), VLF_Group.

Fieldhead — Norfolk / UK — August 2008 (by Julien Ottavi)

Jura Mountain — France — 23 May 2008 (by Brice Jeannin)

VLF recorded with an electric field receiver near the Jura mountains, eastern France. On the recording from 23rd May 2008 at 10 PM you can hear whistlers and a background of tweeks and statics. On 14th August 2008 around midnight, tweeks and man-made radio signals — some are sequences of tones at high frequencies (the Alpha Russian radio-navigation system), others visible on the spectrogram as bold horizontal lines (military RTTY radio stations from different countries).

Recording of VLF activities in Corrèze (France) — July 2007 (by THE NOISER)

17th of July 2007.

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