passenger compartment noise

I am very pleased with my new 2003 VUE except for one thing. There is a low-frequency "booming" noise that resonates in the passenger compartment when driving over rough surfaces, and this noise literally envelops the cabin when cruising at 55-60 mph and is very annoying, so much so that I am now avoiding in-town interstate driving where I am limited to that speed. To be honest, this noise is not a problem when cruising at 65 mph or faster. I would like to know if this sounds like a problem with my vehicle or if it is a design characteristic/flaw, and I would also like to know if there is anything I can do about it. Thanks.