Here's a message from a student and my response, hopefully helps some of your guys out!
Hi Graham, I use D'Addario phosphor bronze extra light strings on my acoustic and don't get much screeching compared to the strings that were on the guitar when I bought it. Hope they have the same effect for you too!
So many variables and a lot of it is so subjective but two things you might not have considered would be your playing dynamics and your listening environment.
If you're picking/plucking/strumming lightly but still getting there with chord changes / fretting /left hand accuracy you might have less dynamic range between the sounds you're trying to play and all of the peripheral noise that comes from working with noisy resonant bits of wood!
Also where you play can make a big difference to the sounds and frequencies you perceive. If you're getting a lot of reflections from high frequencies or high midrange because your playing environment has lots of hard / reflective surfaces - this could add to your perception of some of these extraneous noises. I still think they'll go away with practice though :)