[shorod]

Are you absolutely certain the noise is from the power steering pump and not the tensioner pulley or idler pulley? Does the noise vary if you turn the steering wheel when the car is at idle or does it only change based on engine speed? Have you checked the fluid level? Has any service recently been performed on the vehicle that may have introduced air in to the system, such as some service where the wheels may have been turned manually without the engine running?

-Rod