If you notice the sound only when the wheels are turned, it could be a wheel bearing. Jack-up the front end and give each wheel the push-pull/spin test.
1. Put your hands at the 3 and 9 position and try to move (push and pull) the wheel in-out. If there is movement, it could be an inner or outer tie-rod. I doubt this is the case as you would hear/feel this all of the time.
2. Put your hands at the 12 and 6 position and try to move (push and pull) the wheel in-out. If there is movement, it could be a bad ball joint. I doubt this is the case as you would hear/feel this all of the time.
3. With the wheels up in the air, give them a spin. Do you hear any grinding noise or does the wheel not spin freely? If either exist, then suspect you have a bad bearing. Normally a bad bearing can be heard pretty easily when you are driving and going around a corner or at slow speeds when making a sharp turn.
Hope this helps.