So, when you finish a stage and your ship goes to warp to the next one, sound goes bbbbzzzzzZZZZZZZZZZZZZZ, then it stops a few seconds and it starts again, BBZZZZZZZzzzzzzzzzzz.
This was logical during the normal games, because of the cutscenes and stuff, but here when we’re warping from one stage to the next one, it should remain persistent, so it stays bbbbzzzzzZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZzzzzzzzzzzzz.
Same would apply for interstellar traveling at top speed.
As for the sounds, I always just assumed that the first one was the sound of the warp drive powering up and the second one was the warp drive turning off.