Hello and welcome to our web page here my name isXXXXX a Certified Volvo Car Expert Mechanic.I'm going to try today to answer your question.
can you give me more details please is the humming with inside the car ?with blower fan on or off ?
or if you can record video audio so i can hear would help ?
The humming sound is coming from the engine area when driving . It started off after taking off from traffic lights when it sounded like someone accelerating but later realized it was my car. The sound occurs after moving off when accelerating and is rather inconsistent during driving.