Has anyone found a definitive fix for the fan noise?

I was wondering if there was a definitive fix for the buzzing fan noise that is so prevalent on these models? Over the last few years I've read thousands of posts about it but no one ever had a fix. It gets really annoying in a quiet room.

The noise comes from the vent port in the center of the rear cover (just underneath the hinge. It increases with RPM. If you slightly cover it with your hand (but not seal it off) the noise drops considerably, but the fan of course increases speed to compensate for the restriction. It seems the buzzing noise is amplified as it bounces off the stand.

Any ideas?