What Are The Signs That You Need A New Wheel Bearing?

Since you have a roaring noise while driving down the road, if it is a bad wheelbearing, you can conduct a simple test.
While rolling, if you turn the steering wheel to the left or right and the noise quits, then it is a bearing problem.
When you are driving, if you turn to the left and the noise quits, it is the left bearing. If you turn to the right and it quits, it's the right bearing. 

One of the ways to determine if you have a problem with your vehicle's wheel bearing is to listen carefully and find out if you detect a grinding sound. In most cases, this noise is especially pronounced when you make a sharp left or right turn, in order to drive down another street. You may also detect some vibration if you are driving at a higher speed.

If you have a grinding noise coming from a wheel, it is usually a bad wheel bearing.
It is wise to replace wheel bearings in pairs.
Also, use a high quality wheel bearing.
I suggest a bearing USA made from http://mibearings.com

You will hear a humming sound

It also will whistle like type of noise

If a wheel bearing is going youll hear it humming more so than grinding.

Loud grinding noises as in metal upon metal. As it gets worse and it will it will start making those noises at lower speeds too. If it were me I would have all 4 replaced and be done with it.