When it comes to noise, vibration and harshness (NVH), I’m reminded of that dog-van scene from Dumb and Dumber where Jim Carrey says, “Want to hear the most annoying sound in the world?” and then proceeds to emit an astonishingly awful noise. Annoying as NVH may be, it’s a key metric in drive-system development for e-mobility, and the careful design and manufacture of gears are crucial to minimizing NVH as tolerance variations can result in large differences between nominally identical components.