Loud noise in front of car

Got a noise that comes in about 15 mph and gets louder as you go faster. Didn't sound like a wheel bearing but changed them anyway. The noise doesn't change when you turn left or right. almost sounds like a prop on plane(rumble). Any help on what it might be. reading something about Axle carrier bearing not sure if that would make that type of noise or not. And If so is it part of the transmission or is it replaceable.

Thanks For your time and it is a 2007 G6 Gt coupe