This started on my car at 8000 miles after 6 months of ownership, and it gets worse the longer it goes on.
Its not the fuel pump or the transmission, its the ECU. Apparently the G37 has the problem too and Nissan/Infiniity does not seem very motivated to fix the issue.
There have been several threads on the subject on this board, search "high pitch" and you will find them. heres one:
High pitch noise coming from passenger side
If you turn your head to the left to look out the mirror, you hear it in your right ear. The noise is easily heard over AM talk radio, but most FM will drown it out. However if you listen to AM or if you turn the radio off you will hear the noise for an hour or two after leaving the car.
I am taking my car to the dealer next week and demanding they fix it, if they don't I am going to a lemon law attorney. My main problem with it is 1) it shouldn't be happening and 2) its getting worse.