My ability to "hear" music, both during performance and as part of the creative/composing process, developed in tandem with my progress as a player. I would even say that at some point my "ears" lagged behind, since at some point my initial "talent" was overtaken by my ability to play things that were more complicated melodically and harmonically--stuff I couldn't "hear."
(Quick note: I put all of those words in quotes because I find them contentious and problematic. It often seems that people use "hear" and "ear" as if "thinking" wasn't a part of the process. And I also think "talent" is used far to often. As if playing music is not work and that it's always just super wicked fun for us. Please.)
But back to my story. Kurt Cobain was a different sort of musician. His melodic and harmonic IDEAS (or the stuff he "heard") were far ahead of his facility on the guitar. He was terrible at the guitar. But what he was able to write in spite of it is often remarkable, especially when you consider that most of the songs consist of chords without 3rds.
"In Bloom" is a great example of how to project tonality through what is nothing more than a bass line (power chords are simply reinforced bass notes, in my book) and a melody. Not only that, this two-part construction manages to project a sort of modal mixture: B flat major and B flat minor. And this is NOT a "bluesy" sort of minor inflection, for the most part, but actual B flat minor, with G flats and everything.
Here's a reduced version of the intro/interlude/ending:
Yeah, that's right. I said C flat. Here's my take on this. The melody explicitly outlines a B flat minor triad, but even more jarring is the G flat in the bass, since a G NATURAL is heard in the intro. The really fun bit is the B (or C flat) to A natural. I could call the C flat a sort of Neapolitan in root position, or maybe a tritone sub for V. I think the A power chord MUST be heard as a surrogate V chord. That's its job,and that's what it sounds like. But no matter what you name it, it boils down to a two-note idea: half step above the tonic, half step below. And if you look at the whole line, the bass outlines a C flat 7 chord! Maybe it is just a big tritone sub...except for the G natural in the melody. Man, that G natural is nice!
After all of the rogue flats in the verse, the chorus starts with B flat major:
And of course I feel the need to jump in and say well, yes, of course. By "dominant" I mean a major chord plus a seventh that is a minor 7th above the root. Just trying to appease the one person that reads this and calls me out. That A power chord in the verse is more of a dominant chord in terms of function. And what I've labelled as "II7" (when the backing vocal has an E natural) could perhaps be thought of as V of V, which in turn makes the last 4 measures of the chorus a kind of prolonged ii-V (or II-V)--the C to E flat being, ultimately, a dominant move back to B flat.
So that's a quick outline of this song, in terms of harmonic implication and suggestion. You can do a lot with just a bass line and a melody. A lot of things float to the surface when you combine two lines. I only wish I'd appreciated this music more when it first came out--to hear the music rather than focusing on the technical shortcomings of the band. Maybe he didn't know what it meant. But I don't know where he got those melodies. Which is more important?