GAF 10+23 into IAD

>>1688129 Nothing in flight history that indicates it went back last night or this morning. A/C Registration #144614.

Serious question - if an aircraft is traveling at approx. 400kts directly overhead when do we start to hear it - in other words, has it already gone by? F/U question - if it is on a flightpath that's 50 miles one way or the other from directly overhead, is the sound effect the same?

Mid-Atlantic Galaxy and several tankers