Diagnosing sounds over the 'net, can be tricky. However lets try this:
Does the sound occur when in drive ,foot on the brake, engine at a certain rpm, vehicle not moving? If so, you'll need a trusted assistant to hold the brake, vehicle in drive and apply the gas (only enough for the sound to start and olny for about 5-10 seconds at a time followed by a 30 second "cool down period" in neutral with the rpm around 1500)
While the assistant is doing this you will snoop around underhood to locate the area of the noise and narrow it down from there. Once located post the part or area and we'll try to help you further.

did you check the power steering fluid level??

Roy