Why is there a sound barrier?

supersonic flight used to be an obstacle due to sound barrier and sharp rise in aerodynamic drag. If an aircraft flies at less than sonic speed, the pressure waves create outspeed their sources and spread out ahead of it.The sound barrier, the sudden increase in the aerodynamic attraction that occurs when an aeronaut approaches the speed of the sound and that was previously an obstacle to supersonic flight. If an aeronaut flies a little less than the speed of the sound, the pressure waves (sound waves) create a tracking of their sources and disperse in front of them.