* The Speed of Sound: Sound travels at approximately 767 mph (1230 km/h).
* Supersonic Speed: A plane traveling at 1000 mph is traveling faster than the speed of sound. This is called supersonic speed.
* Sonic Boom: When an object travels faster than sound, it creates a shock wave that we hear as a sonic boom. The sonic boom is heard *after* the plane has passed, not before.
In short, a plane traveling at 1000 mph wouldn't be heard approaching because the sound waves it creates are trailing behind it, not in front of it.
