Some of us oldies will remember twin choke carburettors usually Zenith or Solex or, if you were lucky, Weber. They had two throttles, if you drove the car gently it only used one but if you opened it up the secondary throttle came into play. Point being you got a completely different induction note when you crossed that divide.
Thinking about this humming noise, the Antara has swirl flaps in the inlet manifold (so does about every engine these days, petrol and diesel). So I wonder if this humming noise is related to the swirl flaps kicking in?
2015 Antara Exclusiv 2.2 163ps Manual 2WD