I have installed octoprint and am doing my first print with it on an Ender 3 pro. Print is two knobs for the ende 3, a Z axis knob and an extruder knob
Every now and then (mostly when switching between knobs) the printer will pause, and what can only be described as a "throbbing disco beat" will sound from the printer. Not sure if its from the electronics box or from a motor.
Would add a video if someone tells me how
The stepper driver circuits can be noisy on some boards and the stepper motors themselves make noise. The entire assembly itself has belts, bearings, you-name-it. If gcode is being sent but this is combined with no movement + sound then it's possible that some kind of micro-stepping is being asked for and your rig can't do that; I'm guessing here. Also, if anything is blocking the movement or even slightly hindering it and the steppers can't move, they can make noise.
But then again, my own Smoothieboard for the print job I almost always use for testing is a cam ring and the steppers—I swear—sound almost like they're saying "boy, girl, boy, girl, boy, girl..." in a weird computerized voice through most of that. 