NASA’s Voyager 1 spacecraft recorded the sounds using an onboard plasma wave instrument. This instrument detected the vibrations of dense interstellar plasma, or ionised gas, from October to November 2012 and April to May 2013. The waves detected by the instrument antennae can be simply amplified and played through a speaker. These frequencies are within the range heard by human ears.
Listen to the sounds here: http://bit.ly/16xrtgh
The image is of the central 50 pc (~150 light years) of the Galactic centre showing ionised gas, hot and warm dust. Credit: Hubble Space Telescope, Chandra X-ray Observatory and the Spitzer Space Telescope