Hyundai Repair: whistling wheels, infernal combustion engine, rear drum brakes

Question
I have a Y2K Elantra 2.0. The problem is that when i turn right, there is a whistleing sound coming from the front of the car. it doesn't happen when i am going straight or when i turn left. The front brakes were changed when the car was serviced a few months ago, but the mechanic said that the rears would need doing at the next service. could it be that they need doing now? It doesn't matter if i am applying the brakes or not, the whistling is still there! I don't know a lot about the workings of the infernal combustion engine, but don't want to look a total idiot when i take it to the garage!

Answer
If the noise only happens when you turn, it's most likely from one of the wheels.  If it is indeed coming from the front, it won't be the rear brakes.  Furthermore, if you have rear drum brakes, there are no wear indicators present to make noise.

Another possibility is that one of the front pad shims or the backing plate is out of position and just barely touches the rotor when you turn.

Don't worry about looking like an idiot.  Most shops prefer that you not try to diagnose the issue yourself.  The just want to clearly identify the issue so they can determine its cause and correct it.