LowSS

I'm thinking i've got a bearing going bad somewhere, sounds like the front but I'm not getting any up and down play at the front wheels. Turning the car left at speed reduces the roar. Along with that i'm feeling a small vibration under my feet. I also checked the rear wheels and do get some up and down play but not sure how much is acceptable. Rotated the tires, they look good and no change in the roar, rotors and brakes look fine. With the rear off the ground its quiet at speed. Guess what i'm getting at is whats the best way to diagnose a bad bearing? Hate to just throw parts at it.
thanks
pat