Hard to say, because I can't read music fast enough to play directly from it. I suspect that, except in exceptional people, playing by ear and from music are not completely compatible.

I have no problem picking up tunes after once or twice round, but I have more problem with the words so perhaps what I do with words will me more help. Try listening to a recording over and over again until you are fed up with the tune, humming it to yourself over and over again and generally "soaking it up". I find if I can hum it or whistle it, I can play it on any instrument too.

Cheers!

IanC