Boxster whining
 

2002 986 starts whining around 35 mph. The sound gets higher as speed increases. At speed slipped in neutral and still whines as it coast getting softer as it slowed!

Usually when that happens, I stop the car at the side of the road, and ask my wife to step out of the car :D

After we put a said the most popular joke in the forum, what you are describing sound like wheel bearing going bad.
Lift the car off the ground, and check for play, by holding the wheel on the top and bottom, and pushing it in and out.

+1 on wheel bearing.

+2 on wife.