I agree with Jay, rear tyres or rear wheel bearings, the pinion noise is like a scream not a drone at all
To test the wheel bearings find your self a clear bit of road, get the noise started and then gently weave from left to right and see if the noise changes,
The other question is does it change with gear selection if manual, if auto have you tried selecting gears on the stick manual mode to see if the noise changes
Also the pinion will not stop making a noise at speed it will just get louder
