I’ve long been fascinated by Numbers Stations: Weird shortwave radio broadcasts that transmit groups of numbers, letters, or different types of (patterned) noises. Shortwave radio hobbyists have known about them for several decades, and the best guess is that they’re used by various secret agencies to transmit messages to spies in the field. Nobody knows for sure, because no government will admit to using them.
They’re strangely long-lived, often transmitting on a strict schedule for years and apparently unhindered by political changes; when the USSR collapsed, for instance, several numbers stations suspected to be associated with that government saw an increase in activity instead of going silent.
They’re also often oddly sinister: Most of the letter or number groups are spoken by adult voices, but there’s a station dubbed “The Swedish Rhapsody” which transmits in the voice of a little girl. There’s a station which employs the voice of a woman “intoning numbers as if she were engaging in intercourse.” And a station known as “The Buzzer” transmits high-precision buzzing on 4625khz, 24 hours a day, every day.
In 1997 Irdial-Discs released a 4-CD collection of recordings of these stations called The Conet Project (named for a mishearing of the Czech word konec, or “end,” which is used to note the end of transmission on a Czech numbers station). These recordings are available for free at the Irdial site (near the bottom of the page) and are mirrored here. They’re also available at Spotify and Soundcloud. Irdial has released an interesting project booklet which discusses numbers stations in more depth (and also laments the public’s seeming unconcern about these mysterious stations).
Some of the recordings have been described as disconcerting or frightening, and listening to these weird, lonely signals definitely makes one uneasy. They’re also a treasure trove of audio samples, either to add a little ambiance to a spy-themed party or to remix with music.*
Here’s a sample; for best results, listen to it alone at night.
*As long as you don’t make money from them. They’re completely free for non-commercial use.