Jet sound contribution

I believe not much at all. The biggest sound in a jet engine (the screech as it goes over you) is from unsteady disturbances on the stators (or something like that, as I've been told).

The shock is merely a discontinuity in the flow, and is caused by the rapid pressure drop,raise,drop. Someone correct me if I'm wrong, but that N shock is considered one shock as well.

On a side note, there are various different sounds emitted from a jet engine, and they all produce characteristically different sounds.

 

I forget the exact physics of the particular sounds, but there are two major "sounds" that are emitted by the engine. There is the "screech" you hear as a plane passes directly over you (I'm talking subsonic right now, but it should apply). If you've ever sat near an airport, you know what I'm talking about.

The properties of these unsteady waves allow it to spread at an almost right angle when it leaves the engine. Now, after a couple of seconds, you hear the low rumble. This is a completely different family of pressure waves. Those are higher amplitude, but much lower frequency.

I may be completely wrong, but I think at 50,000ft, the enormous pressure discontinuity would overwhelm effects from the jet engine.

 

The two main contributors to jet engine noise are fan noise and exhaust noise. Fan noise is usually dominated by a single frequency component that is a function of things like tip speed, blade geometry and number of blades. Exhaust noise is highly random and is pretty much as broad band frequency as you can get.