That sounds like an alternator whine. Where have you taken the power feed from. It can usually be fixed fairly easily, but its easier for me to do it that tell you how. I will have a look and a think and see If I can put together an easy to follow fix and the parts required.
You could start by fitting an alternator suppressor to the rear of the alternator. It should be available at repco, and looks like a small can with a lead coming out. The can has a lug that uses a screw on the rear of the alternator, and the lead goes to the +ve out from the alternator