2008 lexus es 350 intermitent humming noise

My car has a intermittet humming sound. it starts at low speed and gets louder as I go faster, but doesn't necessisarily speed up with the revolution of the wheels. 5 mecahnics have looked and can't figure it out. One theory is a bent rim, but the fact that it doesn't evolve to a steady hum as I go faster, quashes that theory. Wheel bearings were changed. The car was damaged from highting a large pot hole. The noise is Whomp, whomp, whomp and gets louder as i speed up.

Hope you can help!