The sound is like a single tone that, over time, changes. The way the frequency moves around as Voyager 1 travels further can tell researchers how the density of the interstellar medium is changing. The hum could also help researchers understand the density of the space between stars.
There has never been an opportunity to track and evaluate this kind of data.
Cornell research scientist Shami Chatterjee, who co-authored a study on the new sound with Ocker, described the data as the spacecraft saying: “Here’s the density I’m swimming through right now. And here it is now. And here it is now. And here it is now.”