According to astronomer Mark Whittle of the University of Virginia, the big bang's sound waves were created during the universe's first 380,000 years when space was still foggy with gas containing free electrons. Once the fog cleared, however, the universe fell silent.
The big bang's ballad is still detectable though, and is described by Whittle as "a descending scream, changing into a deepening roar, with subsequent growing hiss." He adds: "Perhaps most remarkably, within the big bang's sound there is a fundamental tone and a set of harmonics."
Of course, the big bang itself was mute, because it takes time for pressure to act across distances and generate a sound wave. Only later, as the pressure forces crossed regions of outer space and set up sound waves did the latter establish their presence.
Closer to home, the sun has been chanting for billions of years. Convection currents on the solar surface produce pressure waves that travel to the inner corona and back to the surface, causing the surface to broil and vibrate. These deep, three-dimensional sound waves allow scientists to better understand the sun's internal structure.
In fact, the music of the spheres, and even of supermassive black holes, provides insights into the fundamental nature of our universe. Though no living thing on Earth can hear the music of outer space, the cosmos continues its orchestral display. For understanding, scientists watch (and listen) closely—making astronomers the best audience on Earth.