Just a quick-ish question about the power steering on my Murano (2005 SE, 93k miles). Just yesterday we replaced the power steering hose assembly because it had a leak. Today while driving I kept hearing this whine/humming while the engine is running but the vehicle is still, when the car starts moving the noise becomes louder but then gets softer and will sometimes go away but come back again. The whine/humming is especially noticeable when the car is turning left, but even when the car is still and you turn the wheels either direction, the whine/hum gets louder. This noise did not happen at all before we replaced the hose assembly (and by we, I mean we paid a mechanic lol).
Is this caused by air somewhere in the hose and/or pump - if so, will it go away eventually or is it possible to fix ourselves? Do we need to look at replacing the power steering pump? I am getting pretty tired of random noises happening on this car - the engine rattle is enough of a mystery, I don't need any more crap lol.

Thanks in advance for the help/answers!

For what it is worth, for those who care, the mechanic flushed out the fluid he put in when replacing the hose assembly and added in a different brand of fluid and the whine/hum stopped and has been quiet ever since.