NASA begins work to build a quieter supersonic passenger jet

[strategery blunder]

5. The issue with supersonic travel isn't so much the noise inside the cabin; it's the noise outside.

Because sonic booms are loud. They're so loud that when the Concorde was in service, it was required to fly at subsonic speeds over land. The pilots had to get the aircraft over open ocean before they were allowed to accelerate to the supersonic cruising speed.

That restriction played a part in making the aircraft uneconomical (the other major factors being fuel cost, low capacity, and the safety challenges that came to light as the fleet aged). The Concorde pretty much only flew transatlantic prestige routes, and it was not profitable.

If SST becomes a thing again, it is prudent to dampen the sonic boom noise generated outside the cabin, if reasonably possible. That's what NASA is researching.