Pippa wrote: As you were saying it's definitely about not being able to memorize the tunes, if I can hum it I can generally play it. If I had more "by ear" skill I think I could listen and join in more easily, currently I rely quite heavily on the book. I've not been brave enough to take my accordion yet, the chords is a whole extra level of complicated!
To me, this sounds like graduate level playing by ear. I've been to events I suppose are like this, mostly fiddle players running through a variety of folk tunes. Someone will call a tune and start playing it, and the rest will lean up near that fiddle and listen one time through, bring up their fiddles and sort of play along hesitantly, and the third time through they walk away playing the tune. Coming to it from the outside (tuba player), it's impressive. But they benefit from a lot of practice doing that kind of thing, and a large part of that is an ingrained familiarity with the musical idiom, to the point that they know some of a tune before they even hear it. I mean, after you hear the first bar, you might be able to guess pretty well how the 2nd is going to go, and of course overall repeat structure etc. So ... I'm thinking this "graduate level ear playing isn't so much an arcane faculty that is available to a few mental mutants, it's just a matter of endless repetition of similar themes.
As for the bass side ... if it's hard, it's totally worth it in my somewhat biased opinion. Even when you get a written melody, the bass that comes with it will often be pretty perfunctory -- whether written out, or just chord names -- and I think it's fair to say, that's done with the expectation that a good rendition will sort of connect the dots and make it sing. By ear.