Chevrolet: Humming noise on acceleration, chevy venture, engine airplane

Question
There is a humming noise (almost like a single engine airplane)
that increases as the speed of the car increases, and sharply
decreases as car comes to a stop.The sound is not made when
idling or revving the car. It appears to be coming from the right
front. Nothing appears to be out of place or loose.Turning air
conditioner on/off has no effect.
The car is a 2000 Chevy Venture. Any ideas what it can be?

Answer
Steve ;
 Hi -  I would pull off the wheel and look at the brakes , and in the area , there could be something stuck in there and it is hitting the rim or drum,etc. .  ok
and  have you looked under the hood and by the fan ,to see if a stick or something might be stuck up in the frame someplace