Sound is not ONLY the wave in the medium... The waves structures and forms convey infornation ... It is first the vibrating body source which vibrate even in the empty void...We cannot hear it without a medium , that does not mean that sound does not exist as " internal music of the sound source " ...Earth vibrate as any living organism...
Music is the informative qualities associated with the sound source vibrating body ...With or without a medium to convey it message ...
Sound as qualitative information related to a vibrating source composition, a rock or a not riped yet fruit or as a cavernous metallic sphere or as a wood flute , exist as the prime numbers exist and as music exist as the transcendent circle which is perfect exist, before any ears even existed , they exist in the source or call it God ...
Anyway even a black hole has a sound which no one can hear because it is so low only angels can hear it ...But sound exist as sound source vibrating in the void, as a tuning fork will vibrate between stars even if we could not hear it we will see it vibrating....