It shouldn't be that loud. Can you pull the main cable out and grease it? Sounds like it just needs maintenance. May need additional lubrication elsewhere. The head unit of a speedo normally just has a spinning magnet and a spring inside, but there may be some clockwork for the odometer that's acting up.
I hear the high pitched whine of the wheel, but that's the least of your noises. IKU were a lot quieter because the wheel was smooth. You could sand your wheel smooth, but it would throw off the accuracy a bit. Or try moving it to contact a different part of the tire.
Maybe this blog will help?
http://hughsbicycle.blogspot.com/201...eter-look.html