Power steering?

Lately when i have been driving my car I have noticed that the power steering fluid has been getting lower so no doubt its a leak. Sometimes the car is hard to turn and you hear the usual grinding sounds that a car with a faulty power steering pump has. None of that concerns me. I was wondering though what the hissing sound is that is comming from my steering column..its a constant hiss and I was wondering if that had anything to do with the power steering pump or rack or what. Any advice would be appreciated. thank you.

can you describe the hissing sound a bit more? does it occur all the time? or only when turning? do you think it is at all related to the pwr steering? you might check the tension in your pwr steering belt.