The discovery shows it is possible that other planets broadcast the same way making the discovery of Earth-sized objects, currently neigh-on-impossible with the "see if the star wobbles" method, much easier.
What does the Earth sound like? In one word: awful. Classical musicians like Gustav Holst made wonderful compositions inspired by the planets. Others have made songs of the planets with each planet representing moods: Earth being safe and calming, Mars sounding abandoned and scarred, ex-planet Pluto sounding soft and desolate. Count me as one who does not want to hear the radio soundtrack for the planets.
Space may be a vacuum where no "normal" sounds as we know them are heard but that does not mean it is silent. Radio waves from stars, pulsars, and bouncing off objects makes space a very noisy place. Maybe one day man will be able to navigate the heavens not only with star maps but also echolocation like sonar.