2009 Audi A4 2.0T running louder than normal. RPM’s normal, and car seems to be running normal but has started making a loud humming noise that gets louder the faster you go. Had oil changed a month ago and it says the oil is full. Not really sure the cause for this sudden noise, should I have the car looked at? Please help.

 

Had this happen once and it turned out I hadn't pushed the oil dipstick all the way back in it's tube causing a vacuum leak.