You'll need to do some more diagnostics/troubleshooting to pinpoint the problem. It could be anything--sway bar endlinks, subframe bushings, tie rod ends, strut mounts, ball joints, etc.
First, check the subframe bolts to make sure they are all tight. They should be about 85-90 lb-ft. There is one large bolt at each corner of the subframe (4 total).
Then try this:
1. Jack up one front wheel
2. Facing the wheel from the side, grab it at 3 o'clock and 9 o'clock. Wiggle the wheel by pushing away from your chest with one hand and toward your chest with the other, and vice-versa (as if you are trying to "steer" the car left and right). Note any "play" in the wheel.
3. Repeat step two except with your hands at 12 o'clock and 6 o'clock.
4. Repeat steps 1-3 on the other side of the car.
If you ONLY feel play in the wheel at step #2, you are probably looking at a bad tie rod end on that side of the car. I would replace both the inner and outer tie rod ends.
If you ONLY feel play in the wheel at step #3, you are probably looking at a bad ball joint. It could also be bad control arm bushings, but that is much less likely.
If you feel play in BOTH steps #2 AND #3, you could either have a combination of the problems above, or a bad hub or bearing. However, a bad bearing would usually be audible from inside the car (you'd hear the bearing "whirring" or "grating" as the tire rotates.)
If you don't feel play in any direction when you do the above tests, jack up both front wheels and try to move the sway bar up and down with your hand. Do it on both sides and if you notice any play or slop, you probably have a bad endlink.
If you still haven't found the source of the noise, it could be a bad strut mount/bearing. These struts rotate with the steering knuckle when you steer the car. Therefore, the upper mount has a bearing to hold the strut to the strut tower while allowing it to rotate. The mounts have been known to loosen up with wear, allowing slop or play in the strut. This usually gives a sort of tapping noise over very slight bumps but may not be audible at all over bigger bumps. I have this problem and it's very annoying.
Now, FYI, the strut mounts would be the biggest PITA and would probably cost the most money (in labor charges) to fix. The ball joints are a PITA as well. They need to be pressed into/out of the knuckle. The tie rod ends would be moderately challenging for a novice mechanic, but shouldn't take more than 3 hours to do inners and outers on both sides. The inners do require a special tool. The sway bar endlinks are pretty easy (one hour, tops.) The subframe bushings/bolts don't fail often, and they are fairly easy to replace.
How many miles on the car? Any pothole incidents, or accidents?
