Here's some other tips...
Turn Radio on, with ignition off (if possible) - set volume - all the controls - as if you'd be driving - it may be loud with the engine off but this helps you localize the sources (yes more than one is possible)
Listen...
Insert key - any noise (?) - some vehicles have a switch that "turns on the ECM" for a boot process which is quick turn on to "zero out" sensors during start sequence...This also starts a "buzzer" that is the Key-in ding dong...This also may initiate a DTC trouble code restore if any DTC's in transit were stored - all done by that key-in switch...
Turn key to ACC (first detent) - any noise? Note what is heard...
Turn key to ON (turns on dash lights) - note noises and pause here to allow you and the car to "stabilize" - this is where you'd hear a fuel pump hiss, whine or noise, if only for a moment as it pressurized...
Now switch to start - now check for noise...
Some noise changes "pitch" when RPM changes...Then the problem is localized to the engine.
Others are "proximity" and are run thru the ECM and usually are polled sensors. If you've always had this noise - its' not uncommon to find a bolt that grounds the chassis wiring to the vehicle - if there's age, it may have corroded and rusted the connector that grounds those wires to that spot - like Headlights and Spark Coil return - many sensors run a buss ground wire so they daisy chain along it and these "spots" on the daisy chain can be those sources of noise and the wiring then becomes the antenna you hear the noise thru.
Not to sound dumb, but have you have had any rear window damage? Like replacement? The internal defrost/defog wiring has a little "cap" suppressor located by where the wires to power that current hungry beast enter back thru a grommet into the firewall - same could be said for the Fuel Pump and even the EVAP canister.
Might be a good idea to take a moment before winter hits and take off some side interior panels and locate the harnesses - you see zip tied areas as well as several ground block points - especially along the rear taillight - markers and if you have one, even the trailer pre-wired harness for plug in adapters too...
HA:
So this is what I found out today.
I tried what you have asked and others on here too, and this is what I have found.
1.The noise does change "pitch" from low to hight when I get on the gas, and from high to low when gas is off.
2. There is no noise under 1000 rpm.
3. Turn on AC noise comes on at 1000 rpm.
4. Lights on/off no noise.
5. Fuel pump, no noise.
6. noise is worse on AM them SSB.
7.With cruse control on, and just cruising no noise...only if gas is increased or decreased is there noise.
8. Checked all ground straps (removed/reinstalled) Factory/ my add on's
9. No one can here the noise when I transmit on SSB but can be hurd on AM...(.it sounds like I am on a fishing boat).
10. Motor off all is well.
11. Windows up/down makes noise motor no/ off.
12. Coax removed from radio, no noise, coax center touching radio in put no noise, coax ground touching noise.
13. Alt is good, tested at shop, and nothing could be found on computer.
14. All glass is stock, never wrecked, very well keeped up.
I'm scratching my head......