I am still trying to improve my Playing-by-ear. I can read music and while reading I have to play the song many times before I can comfortably play it. However I find I forget it after a few weeks and while not starting over I do need to practice it again. If I know a song by memory I can play it really well and improvise. But sight reading slows it all down. Didn't have that problem with the sax as I only had to worry about the melody.