2006 Prius - Left Front rotational squeaking noise

I have a 2006 Prius (150K miles) with a noise coming from the drivers left wheel. It is a hollow metallic squeak that only occurs while the vehicle is moving. It sounds like the wheel is making brief contact with something metallic at the same point on every rotation. The pitch of the squeak increases with the speed of wheel rotation. It does so while rolling, with breaks and without. The noise gets louder when turning right, and softer when turning left, though it begins to get louder again when the wheel is turned hard all the way left.

The front pads have just been replaced and the wheel bearing at 90K miles. I am thinking it must be something else rubbing making the noise. It doesn't appear to affect driving performance. However, I am worried something is at risk, possibly nearing failure due to the friction causing the sound. If nothing else, it is loud and embarrassing when driving in my neighborhood. If I can't figure it out, I am going to take it to a mechanic next week.

Any thoughts?

~ Dave