Humming noise between certain rev in Ford Focus 2011 TDCi?

Humming noises as youve described are often some thing simple, id check the heat shield for the exhaust there flimsy and always fall down on my thing causing it to hum away annoyingly! hope this helps,,,,, or some thing more sinister is that a wheel bearing could be off check this by shaking the road wheels once jacked up or any garage should be able to tell you for free but the vans are new so i doubt this would be it