2017 That whistle sound

I typically drive with the radio at least at low volume but yesterday I did a whole trip in my 2017 LT with the radio off so I could talk to passengers. I noticed a whistling sound which happens only at one specific throttle position. It reminds me of the sound you get out of a cordless drill when you only press the trigger slightly and the motor makes a whistling sound.

Letting up on the throttle just a tiny bit or pressing it a little more just a tiny bit makes it go away. I'd say the throttle position where it happens is maybe 1/10 throttle, maybe less: about the point where you'd have it if you are trying to hold say 30 MPH.

So my question: I assume this is normal and this is typical of how electric motor power is modulated (like a cordless drill)? It's not very loud but it's noticeable inside the cabin with all the windows up.

Thanks,
Mike