My 2004 Impala is making a noise similar to saying “ahhh” in a metal can with a slight echo when the engine RPM is between 2000 - 2600. I can not reproduce the sound with the car in park, only in motion.
just a wild ass guess, but you might want to get the exhaust system checked. Have them check the muffler for loose baffles. Also check the exhaust gasket between the manifold and the pipe. Another thing to check would be a loose bolt on a heat shield.