Bro please check ur car front right side brake calipers and associated holding/locking pins. I ve experienced same problem in another car.. Brake pads seated in holding clamps may be loose, dry or rusty.. Because even u go slow on bumpy or uneven road.. Tuis noise comes...
Secondly, dont get tensed.. It may not be a serious issue.. Just make a little effort. Please check bumper fittings, mud flap, every thing on right side to check if anything produces that sound.. But as u mentioned that it comes only going over uneven roads, symptoms indicate towards ur brake calipers n pins..
May this solves ur problem.