My car sounds like an airplane taking off

What is your question?

I lost the undercarriage splash/covering that is standard with these types of vehicle, and I have not been in the position to replace it. But I've noticed of late that there is loud booming noise radiating from the bottom of my car every time I try to go over 40mph. There are no leaks or holes anywhere that can be readily seen. I just had the car serviced in Sept.and keep the the oil changed. I am not sure what to do. Could this be something to do with my wheel alignment? or axle? or boots?

What makes this problem better or worse?

driving at speeds higher than 35-40 mph

How long has your 2010 Nissan Rogue had this problem?

a few weeks