By what mechanism or combination of mechanisms does the X-59 reduce the noise produced by a sonic boom? What are the design choices that lead to quiet supersonic flight? I really want to understand the issue from an aerodynamic perspective as well as a design perspective.
The X-59 has not yet flown, but according to the designers...
The ground noise is expected to be around 60 dB(A), about 1/1000 as loud as current supersonic aircraft. This is achieved by using a long, narrow airframe and canards to keep the shock waves from coalescing. It should create a 75 Perceived Level decibel (PLdB) thump on ground, as loud as closing a car door, compared with 105-110 PLdB for the Concorde. The central engine has a top-mounted intake for low boom, but inlet flow distortion due to vortices is a concern.
Additional information on this NASA project is available here.