The result sounds like low, rumbling moans:
Geeven recorded the sounds in a 30,000-foot (that's five miles) deep borehole in Windischeschenbach, Germany. You go that deep into the earth and the temperatures rise dramatically - at the bottom of the Germany hole it was around 500 degrees Fahrenheit. An article on Wired.com explains Geeven's inspiration, and the technical difficulties:
She began researching super deep holes and stumbled across the famous Kola borehole. It turned out that the Kola hole closed down in 2005 and had been partially filled with concrete, so she continued her search until she found the perfect hole in Germany. She contacted the German Research Center for Geosciences and inquired about their hole.
"My question to them was of an existential and poetic nature: 'What does the earth sound like?' I do believe they were a bit skeptical at first about my presence." she says. "The first answer I got from one of the logging specialists of GFZ was straightforward and slightly disappointing: 'Lotte, it's going to be totally silent down there.' "
At its deepest point, the hole reaches a scorching 500 degrees Fahrenheit, a temperature at which normal electronics melt like an ice cream cone in the summer. "My first naïve thought of lowering a normal microphone inside was waived," she says. Instead they used recordings from a geophone, a device that measures ground movement, and an ultrasonic sensor that measures soundwaves outside the range of human hearing. That data was then translated into audio by specialized software.
While Geeven was looking inward, inside Earth, another artist was looking outward, out into space. Multimedia composer Andrew Williams, Artist in Residence at the University of Leicester, recorded the sounds of plasma moving through the sun and of electrons hitting Earth's atmosphere. He calls the resulting sounds "animalistic."
Those sounds are not in the audible range of humans, so we couldn't actually hear them if we could somehow turn an ear to outer space. But scientific instruments can "hear" such sounds, and Science Daily explains how Williams created his audible recordings:
Using data collected from satellites and long-wave radios, Andrew has revealed the similarities of sound created by electrons hitting the upper atmosphere of Earth to a dawn chorus of birds while the low hum of plasma passing through the sun creates a pulsing rhythm reflecting the heartbeat of the solar system.
Andrew explained: "I was quite shocked at how similar electrons hitting the Earth's atmosphere sound to bird song. Collectively, it is surprising to hear that space has an almost animalistic quality to its sounds which I have been quite struck by.
"By transposing sounds recorded by satellites into the audible range, I have been able to present the data as audio, providing a glimpse of what space would sound like if we were there and if the sounds generated were in our audible range."
Here is a sample of Williams' "animals in space" art installation: