Why would it be futile to attempt to detect sounds from other planets, even given the very best in audio detectors?

Issues, in the event that we could hear something it would have been something that happened quite a while prior simply do to the time it requirement it would take to get to us. Furthermore, there is no medium in space to convey the sound wave vitality to us. This would require something that could transmit sound on, it would require a flexible substance like: a strong, fluid, gas, or plasma. Flexible suggests a shape which has iotas moderately near one another that would react to different movements and transmit the compressions and rarefactions of the sound wave back to us on. Without this it would basically resemble attempting to transmit sound in a vacuum and sound does not go in a vacuum.