[rplnt]

It's not about the noise in general. It's about the sonic boom. For example, Concorde's sonic boom: http://www.youtube.com/watch?v=oMOyeuDKAlg

[rbanffy]

Indeed - a sudden boom is more disturbing than a rumble.

Still, if it can be made quiet enough not to scare people, it could be inspiring. You hear a bang in time see a man-made object traveling above Mach 2.

Or 3, 4, 5...