Sonification: Listening to the Haunting Sounds of the Universe

Swirling arms of galaxies stretching hundreds of light-years across. Delicate watercolor-like strokes of gas emissions and the pinprick dots of newly born stars. The faint light escaping from the dense and disastrous event horizon of a black hole. For many of us, the wonders of the universe are unlocked through beautiful pictures, released on a regular interval from NASA's various observatories and telescope missions. Photos — and all visual media — are an incredible way to learn about astronomy, but they aren't the only way to see — or rather hear — the universe.

Sonification is not a new technology; it dates back to 1908 with the invention of the Geiger counter. However it has lately seen a resurgence thanks to some incredible projects that have helped spark even more curiosity in NASA missions and the deepest reaches of space that they're peering out into.

What Is Sonification?

Before attempting to make sense of the haunting sounds of the universe, it helps to have an understanding of how those sounds came into being. The process is called sonification, and we were able to learn more about it from Matt Russo, astrophysicist, musician and the presenter of a TED Talk fittingly titled "What does the universe sound like?"

"Sonification is the use of non-speech audio to convey information," Russo explains. "It involves converting data into sound so that the relationships within the data can be perceived, explored and enjoyed with our exquisite auditory system."

In short, sonification is taking data and making it into sound. NASA has been doing this with a variety of interesting data sets lately, including the black hole at the center of the Perseus galaxy cluster, which Russo created the sonification for.

There's actually an entire library of sonification projects, which NASA calls "A Universe of Sound," where the listener can aurally explore deep space objects ranging from the "Pillars of Creation" in the Eagle Nebula (Messier 16), which is 7,000 light-years away; to the Tycho Supernova, which occurred in November 1572; to the Chandra Deep Field data, which capture some 5,000 supermassive black holes in a single image.

Big Bangs and Black Holes

Sonification usually makes headlines in scientific circles when the final, beautiful results are released about some new phenomenon. Maybe that's a black hole or an emission from a dying star, but sonification can be done with any data set that NASA has.

"In the same way that any data can be visualized, any data can be sonified," shares Russo. "[S]ince sound happens through time, it's usually more effective to sonify data that represents something evolving over time. This could be pulsing radio waves from a pulsar, gravitational waves from colliding black holes, or the fluctuations of a resonant variable star." So those fascinating astronomical phenomena are great candidates for sonification, which is why we hear so much about them – literally.

But sonification goes beyond creating a new medium for large data sets from distant places. "Sonifying NASA's iconic imagery data presents certain challenges since images are essentially fixed in time, but it also leads to novel and creative mapping strategies that seem to spark people's curiosity," Russo says. Sonification is in fact an important tool for improving science literacy, since humans learn through a variety of media.

There is also a more practical accessibility reason for producing sonification of astronomical data: "It's also rewarding to help someone who is blind experience the beauty and wonder of astronomical images," Russo shares.

Closer to Home(ish)

Sonification doesn't exclusively need to be used for interpreting data from light-years away; there are applications for the technology much closer to home. "The InSight lander has been recording marsquakes from the Martian surface for the past three years, including a massive quake within the past few days," says Russo. "I'd love to work with seismic data to give people a sonic experience of the ground rumbling on another world."

For any of us who have experienced an earthquake and heard the rumble, it will undoubtedly be captivating — and a little concerning — to finally hear a marsquake.