Today we’re having a listen in on Sounds of the Sun – audio recorded by the ESA and NASA and processed for human ears. These sounds originate from data captured by the ESA (European Space Agency) and NASA’s Solar and Heliospheric Observatory (SOHO). After data was recorded, it was sonified by the Stanford Experimental Physics Lab. Sonified! Let’s talk about what that means.
To sonify is to map data to sound. That is, to place a set of rules between one dataset and one end product: a set of mapped sounds. This is a method with which unreadable, un-seeable, or otherwise inaccessible data can be consumed. Have a listen to the sun here and we’ll take a stab at understanding how this was made.
“[A. Kosovichev, Stanford Experimental Physics Lab] started with doppler velocity data, averaged over the solar disk, so that only modes of low angular degree (l = 0, 1, 2) remained,” wrote Katie Atkinson and Micheala Sosby from NASA’s Goddard Space Flight Center for NASA dot GOV. “Subsequent processing removed the spacecraft motion effects, instrument tuning, and some spurious points.”
“Then Kosovichev filtered the data at about 3 mHz to select clean sound waves (and not supergranulation and instrumental noise). Finally, he interpolated over the missing data and scaled the data (speeded it up a factor 42,000 to bring it into the audible human-hearing range (kHz)).” Additional solar sounds can be found on the decidedly Web 1.0 internet website Sanford SOI site.
Above you’ll see a SoundCloud file ripe for the tapping. This file was produced at NASA’s Goddard Space Flight Center by Katie Atkinson and Micheala Sosby. It contains an explanation of “how this simple sound connects us with the Sun and all the other stars in the universe.” You can download the file as well by tapping in to SoundCloud – consider it a podcast. They’ve got a bunch of other NASA-related sound files there as well, podcast style. We’ll expect a regular appearance by The Sun on the program now too.