When will I hear the sonic boom from a plane flying towards me? When does a person first hear a plane, flying faster than the speed of sound, as it flies directly overhead? Yes, I know there is a sonic boom and I also know the plane will produce sound as it flies away from that person. But what about the sound that the plane produces as it's flying towards the person? Will the sound be different from the sound heard after the plane has passed?

My dad and I have discussed this and looked at a partial explanation on Youtube, but there wasn't anything - as far as we could find - on the sound produced when the plane was coming towards a person.
In case a supersonic aircraft (flying faster than the speed of sound) flies directly over a person, that person (the observer) will not hear anything.

The (supersonic) aircraft produces sound throughout its flight (i.e. while flying towards as well as away from you). 

The sonic boom you hear is the sound produced by the aircraft when it was coming towards you.

For how this works, see this question and the Wikipedia page.