With two recent questions:
I found myself looking for a acoustics tag with no luck. Nothing comes up in the tags when I search for "hear" or "sound" either. We have a senses tag, but that does not include the science of acoustics.
Finally, I found audio.
For questions asking about the creation and propagation of sound (compression waves) in any medium. Questions using this tag should be asking about general world rules such as the nature of sound in a specified atmosphere or the consequence of sound given a magical event.
Questions asking about how creatures or beings speak or vocalize should not use this tag, but should instead us the vocalizations tag.
Questions asking about music should not use this tag, but should use the music tag instead.
To make it easier to find (only 4 questions before my retags), can we add acoustics as a synonym? I can't propose it because I don't have a score of 5+ for audio (and synonym proposals are nearly invisible anyway).