How much noise does flow separation cause? I recently found the following image showing the different sources of noise in vehicles. I notice that Aerodynamics is actually quite a big part of vehicle noise, as shown below by the blue line:



Image source

I can imagine this is partly because of the flow going over the car. However, I think a part of this noise also comes from separating flows (for example at the rear window).

I was wondering if it is possible to reduce the aerodynamic noise of vehicles by applying separation control.

As such, I'm wondering:

How much noise does a separating flow generate?

I'm guessing this highly specific to the local geometry and velocity, but I would already be very happy with some examples.
Flow separation makes a lot of noise. Usually, it is masked by engine noise and/or damped by insulation. Any pilot of a light plane may climb to a safe altitude and then idle the engine, start a glide, and then slowly pull the stick until the wings start to stall. He will hear a lot of noise, and feel a strong vibration, too... The cause is the turbulence associated with the flow separation.