When a jet flies faster than the speed of sound, does the pilot hear the sound of the jet? What is exactly behind teh sonic boom? What causes it?
If nothing else, a considerable amount of the noise of the engines is conducted through the body of the jet itself.
As to what is behind the sonic boom? I’m not sure I understand exactly what you are asking.
The “sonic boom” itself is a shock-wave phenomenon that occurs when an object travels at supersonic speed.
What I meant was what causes the sound.
Here’s another question, if it were possible to have the hatch open and someone sitting across from you going that fast, could you hear the other person talk (aside from the noise).
Aside from the noise, yes, you should be able to. However, you’ll be pulled out of the hatch. 
LL
When something goes the speed of sound, it catches up to it’s own sound waves. But, as it catches up to those sound waves, it is still producing more sound waves. The effect is that all of these sound waves get superimposed on top of each other, causing one big sound wave. That’s probably the most basic description, if I didn’t do it justice, someone else feel free to jump in.
Also, Mach 1 is the point where the air can no longer move fast enough to get out of the way, hence the shockwave, the “piling up” of sound waves, and the heat generated on the skin of the aircraft.
The shockwave is caused by the build up of energy in the transonic zone - the plane vibrates and then causes a shockwave as it breaks through its own sound waves which have built up in front of it. You would not be able to hear a plane approaching you if it was travelling faster than mach 1 until it hit you. The pilot does hear the sound of the jet because the vibrations travel up through the plane itself. Sound waves travel faster in liquids and solids than in air, which is why Chuck Yeager broke the sound barrier high up, as the speed of sound is slower in thinner air.
Cool, got it. Thanks.
Just to pick a nit in Nukeman’s 99.9% correct post, but air is a liquid.
Sorry for the trivial adjustment. I, and I’m sure everyone else here, knew what you meant.
How so?
Nitpicking a nitpick: Air is a fluid. Not a liquid. Air (gases) and liquids are both fluid, and behave according to the same laws.
Yes, yes. How foolish of me. Sorry.
yes, what are you on about connor?
air can be a liquid though. you just have to cool it or squish it enough. So what I should have said was ‘sound travels in solids and liquids faster than in gases’
Also kilt wearin’ man: the air molecules dont exactly ‘get out of the way’ they dont go ‘oh shit, theres a plane coming quick! get out of the way’ the air is formed into slightly denser areas by the sound pressure wave and as the plane is catching up with these they build up.
Dreading to pick a nit with Nukeman after the last exchange, but the speed of sound in air is more dependent on temperature than density. The reason the speed of sound is lower at high altitudes is primarily because it is colder (although the density is a factor). The thin air is very important, though, because the drag on the aircraft is greatly reduced. The same thrust that can produce supersonic flight at 30,000 feet might be insufficient at sea level because of the higher drag forces.
FWIW, the “boom” you hear is technically the reaction of the air to being shocked, not the shock wave itself. After the shock wave passes through the air it re-adjusts itself to the new conditions created by the shock wave’s passage. The air molecules move to make the adjustment and moving air = sound. Because of this the pilot will never hear his own sonic boom. He will be moving away from the sound before it is created and, obviously, it won’t be able to catch up.
Sorry, Pluto, youre right: at sea level on a warm day its about 760 mph, wheras if it is 60 below (ie at 40 000 feet) its only 660 mph. Chuck Yeager broke the sound barrier in the X1 at about this height. (He was a hard bastard. He had two broken ribs at the time)
It would seem that by now they could have found a way to soften the sonic boom, so SST’s could travel over land.
The thing that comes to my mind is changing the shape of the wave so it interferes with itself and jumbles or becomes dissonant. Perhaps extra flaps or spoilers on the wings or tail to give it an internal “echo”, just slightly delayed, that would be the seed of it’s distruction.
Well, I didn’t think the plane came through saying “excuse me, pardon me…” to which the air replies “oh, by all means, after you…”
As for hearing an approaching plane, if it’s at high-subsonic speeds you don’t hear it 'till it’s right on top of you either. Doppler effect. If you live under a well-travelled path between Air Force Bases you’ll get almost weekly demonstrations of this phenomena (it was a highlight of my childhood…). I remember on one occasion a flight of four F-4 Phantoms came over at about 2000 feet and pretty close to mach 1 (probably about 650 mph). I saw them fly over and a split second after they passed overhead the noise arrived and every window on the house started vibrating. If they’d been flying supersonic, the boom probably would’ve busted every window in the house. Of course it’s strictly against AF and Navy regs to go supersonic over populated areas for just this reason…