Assuming it is a scroll compressor, you can get a compressor blanket that wraps around the compressor inside the unit. It does a decent job of quieting the higher frequency noises.
its not the high frequencies that bother her, its the low hum of the unit
which is almost humorous, seeing how deaf she is. but somehow, she hears the AC...even with her fan blowing
that's her approach to the situation
last night I came home, and it was 78 inside the house since she did turn it off
I wouldn't mind building a shed around it, but my only concern would be drawing in enough air to supply/cool the unit
(provided it needs air, I don't know)