No need to change the bearing unless it has developed a problem. Either it will be noisy or it will develop slack. Noise you can hear - it is the loud whining noise when the car is running. Also, it may not have the noise always - some bearings make noise only sometimes. Lowering the windows helps you to hear it more clearly. Slack is checked by lifting the car (home mechanic can jack it up), grabbing the wheel and wiggling it perpendicular to the plane of the wheel in horizontal and vertical positions. If there is any movement (slightest too) bearing has developed slack and it needs to be changed.