My new A4 1.8T has produced squeal almost from the day I drove it home. The noise usually diminishes after a few stops. "Squeal," the term for high frequency brake noise, is annoying, but not an indication of a safety problem with the brakes.

I am a research engineer and I worked for several years on brake noise and vibration problems/solutions for my company's friction material and braking systems division. Noise and vibration are TREMENDOUS problems for auto companies - all of them. The cost of dealing with the brake noise problems customers bring to dealers has the atttention of the auto manufacturers. But the solutions to noise problems are difficult to solve due to the large energies of braking, the resonance properties of the lightweight materials used in modern vehicles, and the changing characteristics of the friction surface as a function of brake temperature, pressure, moisture, friction pad and rotor thickness -- and more.

We should let our dealers know that squeal noise is present, but to insist that they do something about it is likely to do more to drive up the costs that we eventually pay for our next car than to improve the noise from the present generation of vehicles we drive.

More significant to drivers is what is know as "judder." This is the result of uneven rotor wear that causes vibration during stops from speeds above 40 - 50 mph. A change of rotors and friction pads can fix this problem. Beware of differences in aftermarket parts from that of the OEM parts your Audi shipped with when you go in to fix this one.