There's no tag for noise or engine-noise, sound, acoustics, or any related thing I could find. I'm wondering if anyone else has come across a lot of questions involving these things, and if there should be a generic acoustics tag.
I haven't seen a lot of questions coming across our stack that have to do mainly with acoustics. You will a few, here and there, that deal with "noise" (like fooot said in his comment), mainly from engines and a couple from sonic booms.
But there aren't many Aviation.SE users that are asking really advanced questions about sound (like surface reflectivity, dampening, harmonic waves, etc etc). In fact, if they were I'd almost recommend moving the questions over to Phyics.SE.
Though, I will say, if we start seeing a lot of those questions I think a tag would be in order.