TL;DR Determining the root (bass) note of the chord is critical to understand what the harmonic function of the chord is.

One other point: music can be thought of a series of resolutions.

That means that a chord isn't so much defined by what comes before, but what comes after.

Most harmony can be understood as one of these, and sometimes functioning as more than one:

I-IV-V: These chords can freely move between each other. Example: C-F, C->G, F->C, F->G, G->F, G->C in the key of C
Circle of Fifths: The 5 of the chord is the root of the prior chord. Example: G -> C, since C = C-E-G, and the prior chord was a G of some sort.
Stepwise or Chromatic Root Movement: The root of the chord moves up/down to the next letter or stepwise note. Example: A -> Bm
Change one Note The note that follows only differs from the prior by one note, often a stepwise change. Example: C (C-E-G) -> Am (A-C-E)

By "sometimes functioning as more than one", you can see the movement G -> C as a I-IV-V movement and/or V -> I circle of fifths motion.

For example, I was looking at the song Kaerou by Fujii Kaze, and it's got some really nice progressions. Here's one bit:

Amaj7 Dmaj7 C#m7 Fdim F#m7 Em Edim Dmaj7

My reading of the progression is:

Amaj7 We're in the key of A for the moment
Dmaj7 simple I -> IV (I-IV-V movement)
C#m7 stepwide downward root motion
Fo what's this dissonant sound? have to see where it goes.
F#m7 oh, the Fdim interrupted the C#m7 -> F#m7 circle of fifths (V -> I) movement
Em continuing to move stepwise down, setting up an expected ii ->V circle of fifths progression
Eo another wtf chord, I need to find out where it's going to figure it out
Dmaj7 cadence back to I, so I treat the Edim as a tension chord, functioning as a sort of funky V7

Back to my point: for much of this lazy analysis, I could just look a the bass note and ignore everything else, and pretty much get the same understanding.

-- David Cuny

My virtual singer development blog
Vocal control, you say. Never heard of it. Is that some kind of ProTools thing?

BiaB 2025 | Windows 11 | Reaper | Way too many VSTis.