Humming noise

I'm guessing it's a bearing noise. If it's in the drivetrain, you should be able to hear it under the vehicle with a stethoscope with the vehicle safely on 4 stands and your assistant running it up to 25 MPH - BE VERY CAREFUL!. I'd guess it's in the differential. If you need a Toyota specialist, here's a directory link for you: https://repairpal.com/toyota-repair-in-brooklyn-new-york