On Willow Logic:
What do you think is the meaning of the line,
'It took big waves of discipline to learn they pump the birdsong in?'
This line haunts me, yet I can't claim to understand it.
I think that it has to do with the delicate and slow process of recognizing the artificial from the actual. The image I got was a zoo, or bird house, or maybe even a theme park with fake nature sounds. In order to realize these sounds (or other objects) are fake, it takes patience and maturity. Just my take.
-Jenna
As a Kingston boy, I think of life inside the prison walls - and then along the lines of Jenna's response.
Awhile ago, in art and literature, birds sometimes (not always) seemed to represent our limits; we couldn’t fly before the advent of “heavier-than-air flying machines“. They sometimes also symbolized our dreams and such, giving rise to other phrases like ideas “taking flight” and a dreamer having their “head in the clouds” etc. But in recent years the symbol of the bird, any bird, has come to symbolize nature. So it would be perfectly clean to allude this to a sense of something natural. Then “birdsong”, specifically, would be analogous to “natural music” by this allusion. I think on the surface this line plays as the pretentiousness of being completely natural and unabridged as the “true path” but later (after years of performing and touring and making music perhaps?) realizing that the natural feeling music radiates is not so natural at all. But, descending deeper still, we could also go with the old meaning and say that by “pumping the birdsong in” that they are actually pushing it (whatever ‘it’ may be) full of creativity or wishful thinking. Maybe filling a song full of awesome lines or filling a life full of faith. Much like all the lyrics, I think it’s meant to be ambiguous but not ambiguous in the sense of being nonsensical. I don’t think any writer writes utter nonsense and tries to trick people into believing there’s some hidden wisdom. I think they are saying something but leaving it up-in-the-air for the masses.
Hmmm. All valid, but here's the thing: that song appears (at least, to me) to be about an abusive or at least very negative relationship between parent and child. And it seems---I think---to be told from a position sympathetic to the the child's point of view. Much of the lyric concerns how she feels, documents her inner world.
If that's right, then the question becomes how this line makes sense within the wider context of the lyric. The child has discovered that 'big waves of discipline pump the birdsong in?' Birdsong signifying, say, beauty, joy, happiness, music, creativity, whatever? OK, but how does this insight relate to the wider lyric?
Another possibility is that the 'they' in this line is the eponymous 'they' of casual conversation (as in, 'they say alligators live in the sewers of New York,' etc.). So the discovery made by waves of discipline is that the birdsong is something pumped in, rather than indigenous to the space the child inhabits. But again: what does this mean in the context of the song?
I know I'm making mountains of molehills...but for some reason this has been stuck in my craw since I first heard the tune.

hock:
The discipline isn't what allowed the birdsong in; it's what it took to realize it that the birdsong is fake (my take is like Jenna's).
The child is halfway between taking genuine comfort from artificiality - i.e. letting herself be "fooled" by thoughts of beautiful things and a naive vision of the world - and being cynical and hardened by the world. So she's struggling with reality, but still leaning on sugar-coated childish thoughts to help her go to sleep.
Telling these lies to yourself - that all is well, everything is here forever, and the birdsong is real - is comforting, but it's also dishonest and as you get older you make this transition. You struggle with that transition: "It took big waves of discipline to learn they pump the birdsong in." You realize that some of those things from your childhood were fake - they were just pumped in - and you get over it.