A loud, abrupt, shocking noise is jarring. If the sound of your telephone ringing is jarring, it will make you jump.
The jarring noise of the garbage truck screeching to a stop in front of your house might make your dog bark furiously, and a sudden jarring sound from your car's engine means you should probably pull off of the highway to find out what's wrong. Other things that shock or disturb you are also jarring. The word comes from the verb jar, "to disturb, perturb, or produce a harsh sound."