LR2 2008 Makes loud sound when driving

[iskm2u]

Hello
My LR2 2008 has been having problems recently. After having my car fixed at the dealership my car sounds weird. When I go from 0~30mph the car roars making a very loud scooter-like or dirt bike-like sound as the RPM goes up. It gets even louder from 30~60mph. After 60mph it gets quiet. So whenever the rpm goes up the the car gets loud, but when the rpm goes down it gets quiet. When the rpm is stable it's quiet. Any ideas on what the problem is? Many thanks in advance!