According to users on Reddit and the Apple Community forum, the old radio-like noise isn't coming from the USB-C cable or the ...

You may not have noticed if you're a little younger, but computers these days are just so quiet—not that I really have a complaint about that. Silent computers are better for concentration or to enjoy ...

The only real way to diagnose the problem is by trial and error. If you think it is the power supply, swap it and see if it still makes the noise.