2001 Toyota 4Runner Noise

I have a 2001 4Runner that has 157k on the engine. I have noticed that there is a clicking type of noise when the car is idling. The noise gets worse as the rpm's increase and I am not completly sure at what point I cannot hear the clicking anymore because of the speed at which the vehicle is moving so I have to assume that it continues throughout the rpm range. The sound is coming from the front of the engine which makes me believe it is a belt or pulley problem. The belt is not shinny or frayed in any areas which then makes me think it might be a pulley problem. I am not sure how to test for this. My friends dad said it might be a clicking alternator but once again I dont know how to test for this. What do you think might be the problem/solution?