text: if you are on a plane travelling faster than the speed of sound? would you be able to talk to the guy in front of you? the air inside the plane is effectively still relative to you.  it would be no different to sitting in a stationary plane.  however, a pilot in a supersonic plane can't hear his engine sound transmitted through the air outside, only the sound carried through the plane structure and the air inside.  when he or she is on the ground with the engine firing, they can hear the sound of the engine outside - or could if the helmet and cockpit canopy didn't muffle it.