[Sammus]

They often change volume and sound depending on the car, or if you have the wheels on the ground or if your touching the motor (absorbing vibrations).

In my CRT they sound really funny, I think because its all alloy on alloy with a metal pinion/spur, it sounds like its all fuzzy haha. But yeah sometimes ive noticed they go really quiet too. kinda cool how it plays you tones like that i reckon :P