These are some of the hardest to remotely troubleshoot. Sound is very difficult to record and share.

Often a quick look under the car can identify the obvious culprit. Your best bet is to get the car on a lift, and hold the engine at the RPM you suspect to be an issue and listen under the car carefully.  Sometimes it can be transferred vibrations making the change in the center console vibrate. We've also seen a harness buckle vibrating against a bolt. The moral of the story is don't assume, and take your time properly diagnosing what you're hearing.

The most common cause we find is a loose heat shield contacting the exhaust.