Rear suspension noise in your vehicle is an indication that, obviously, some part of your suspension is not functioning properly. But, what could it be? While there are numerous parts to a suspension, there are, fortunately, only a few major components that commonly fail. Before you take your vehicle to a mechanic, you'll want to troubleshoot the problem yourself so that you know what's wrong.
Listen for a metallic clunking sound when going over bumps. If you hear a "clunk" as though two metal objects are banging together when you go over bumps, it's because two metal objects are banging together. The clunking sound is most likely the bushings, or lack thereof, in your upper and lower control arms. These bushings cushion the stress on your control arm joints. When they wear out and disintegrate, the only thing left is metal. When you hit a bump in the road, the joint bangs against itself. You'll need to have these bushings replaced.
Check for a squeaking noise accompanied by excessive bouncing when going over bumps. If your vehicle bounces after hitting a bump in the road and makes a squeaking noise at the same time, it's an indication that your shocks are worn. The shocks control the spring bounce travel. If the springs are allowed to "bounce", it means that the shocks are no longer able to control the travel in the spring and need to be replaced.
Listen for a metallic whistling or winding sound (which could also be described as a mix between whistling and grinding) coming from the lower suspension. This is a clear indication that the rear wheel bearings are worn and need to be replaced.