Let's say like that: the sound is how WE (and the most part of the creatures from the relm of the Animals) percept mechanical waves.
What is a mechanical wave? Any physical disturbance in any kind of matter... So, if u drop a rock in a lake, u'll see mechanical waves. If u put ur ear in the middle of this waves, u'll hear the so called "sound". That's the an easy example.
Well... If u are in a starship, u can hear the "sound" of the engines, guess what? Cause the entire ship structure will be vibratin, and this will pass on to the air inside the ship! But, if u are out of the ship, u'll possible hear nothin, 'cause there isn't enough matter to pass the waves on. Even if u put ur ear in the hull of the ship, 'cause u will have nothin between ur internal ears and the ship hull!! ha!
EDIT:
Mechanical waves don't have nothin of MICROSCOPIC, Dab... Sorry bout that.
EDIT 2:
Let's stop this discussion. Post replies on Angel's new tread. This is a FACTION SYSTEM CLAIN post, man!
"When a man lies
He murders some part of the world
These are the pale deaths which men miscall their lives
All this I cannot bear to witness any longer
Cannot the kingdom of salvation take me home?"
HETFIELD, James; ULRICH, Lars; & HAMMETT, Kirk
METALLICA - To Live is To Die
