NASA's X-59 plane is aiming for a sonic thump, not a boom

"The X-59 is designed to pierce shockwaves created when aircraft top the speed of sound, reducing sonic booms to a muted sonic thump that won't deafen folks on the ground."

"It's a fully new aircraft with parts from all kinds of other airplanes, mostly to save budget and cost. If you can get anything you can reuse, that saves money."

Read at Theregister