The physics of sound waves
The spectrum of light that we really understand is very tiny compared to the much-extended spectrum of possible light, extending from gamma-rays to radio waves. Signals that can be transformed to sound make up only one part of that spectrum.
The way humans and creatures hear sound is, sound streams travel within the air and ultimately reach the ears of the listeners. Inside, they recoil into the eardrum, which starts to vibrate. Those waves pass within small bones in the ear and cause small hairs to vibrate. The hairs appear like small aerials and transform the fluctuations into electrical signals that race to the intellect through the nervures. The brain then translates that as sound and identifies the pitch and tone of the sound.
What about sound in space?
Everyone has tried the line used to promote the 1979 movie “Alien” – In space, no one can hear you scream. It’s actually quite accurate about sound in space. For any sounds to be discovered while someone is in space, there have to be molecules to fluctuate. On our planet, air molecules vibrate and transfer sound to our ears. In space, there are fewer (if any) molecules to deliver sound waves to the ears of people. Plus, if someone is in space, they’re expected to be wearing a heavy helmet and a spacesuit that wouldn’t let them catch any sounds because there’s no air to transfer it.
That doesn’t mean there aren’t vibrations passing through space, it’s just that there are no molecules to pick them up. However, those discharges can be used to produce artificial sounds that are not the original sounds a planet or other objects might make.
Are we really “hearing” a planet sound?
The planets don’t produce a lovely melody when spaceships travel by. But, they do give off all those radiations that Voyager, New Horizons, Cassini, Galileo, and others can collect, and communicate back to Earth.
However, each planet does have its personal, different tune. That’s because each of them has various wavelengths that are transmitted due to different amounts of imposed particles flying nearby, and because of the multiple magnetic field forces in the solar system. Every planet’s sound varies, and so does the space around it.
Astronomers have also transformed data from satellite crossing the boundary of the solar system termed the heliopause and directed it into a sound. It’s not affiliated with any planet but does show that signals can come from various places in space.
How do data collections become sound?
The music we listen to on streaming services, our phones or personal players is simply encoded data. Our music players reassemble the data into sound streams that we can hear.
In the Voyager 2 data, there were no actual sound waves. However, the compound of the electromagnetic winding and particle waving frequencies could have turned into sound in the same way that our music players turn it into sound. All NASA did was, took the data collected by Voyager exploration and transformed it into sound waves. That’s where the “songs” of different planets came from.