There's two significant sounds that are missing on the 385s in the preview stream. It's the pitch change in the IGBT and VVVF drive. There are two points where it's missing. Firstly when the train starts to pick up speed, the initial IGBT whine rises in pitch continuously. Then after around 25-27mph, the whine abruptly changes to a deep hum from the VVVF drive. You can hear it here. Overall the motors and inverters just don't sound as full and detailed as they are in real life.
The IGBT is the VVVF drive what you're describing as deep hum is the synchronous modulation, which causes something to resonate, therefore making it sound even deeper than it is
