[Diblue]

Just on a guessing thought here, without much other info on it, could it be a wheel bearing? They tend to make a clunk clunk type of sound while driving, and on turns. If you think that might be it, just walk up to the car, and try to rock the tired in and out of the wheel well, and see if it rocks. If the whole car rocks, that's fine of course, but if your tire is rocking back and forth, you might have a bearing going bad.

One other thought, does this sound change with your speed? like a winding up or winding down sound? or just a clunking sound?