[denisond3]

I dont know what it might be, but tell us how many miles are on the car, and whether the tires are stock or a wider/lower profile shape. Have a close look to see if the plastic inner fender liners are all intact, not drooping onto a tire. Also look for any shiny places on the stuts close to where the tires spin past.
And is the noise gone when you are going faster than 15, or is it just drowned out by wind noise and tire noise? A bad wheel bearing generally makes more noise the faster you go, and can become totally silent when the wheel is jacked up in the air; because the failed part of the bearing can be the upper part of the outer race - which has no load on it with the tire in the air.
Every tire-with-a-worn-tread-pattern I have heard also gets louder as you go faster.
I use the technique of driving along parallel/close to a high brick wall (like the back side of a Costco or Walmart) with the windows down. The wall reflects sound and can help you analyse noises.