I rarely hear musicians discuss harmony, but that doesn’t mean that it’s not on their minds.
They discuss sound, and here’s how it usually goes: “What’s that chord?” “Which one” “The funny one?” “Oh that, it’s this…” bling, strum…“Oh right, thanks, that’s cool.”
So what if you’re writing and you come up with something that you don’t know what it is? A natural impulse is to rely on training, whatever that may have been (school, books, gigs etc) and analyze your idea with chord symbols. This involves mentally stacking the notes in a way that makes sense. That’s what we’re taught to do. Then we might ask “where does it go? what key are we in? what’s the associated scale?”
A drawback to thinking in terms of chord analysis is that it’s after the fact, and usually chord symbols say nothing about their actual application and tonal function. Our perception of harmony is dependent upon what we perceive as a progression or movement of voices that imply tension and resolution (or not)–tonality (or non-tonality) develops over time, and has as much to do with orchestration, texture, style and voicing than with what the actual “chord progression” may be. That’s why a simple melody can imply harmonic movement, and two voice counterpoint can sound full and tonally complete, even with no “bass.” That’s why we can hear a progression in our heads while we’re listening, even if nobody is playing chords.
If you stop to analyze a chord, especially when you’re writing or improvising, you break the flow and the process grinds to a halt. If you ask “where can it go?” like you learned in theory class, you’re screwed, cause the chord doesn’t write the music, you do. You can make it go anywhere you want, and call by any name.
I like calling chord structures this, or thinking of a short description, like “this moving up over a pedal point.” If I just wrote it or improvised I might intuitively know what it is without naming it, and without disrupting its sound by putting the voices in order of root, 3rd, 5th etc.
Now consider the difference between a Eb/B chord and a Bmaj7#5, two chord ideas with common pitches yet distinctive sounds. Play an Eb triad in your right hand: Bb-Eb-G, and stick a B bass note under it in your left hand. Now compare that sound to Bmaj7#5: B-D#-G-A#. The presence of the B now in the upper register changes the sound. The stacked thirds have a certain ring, so different from the Eb triad over a B bass note. Moreover, the symbol Eb/B demands no B in the upper register, and with good reason: it’s a different sound than Bmaj7#5.
Then how ’bout the structure: A#-B-Eb -G? This might be called an “inversion,” but really it’s a new sound altogether. The half step rub at the bottom changes everything.
Slide the A# down an octave or two into the bass register, and the “chord” is Baug/A#–that looks bad on paper, and also implies an augmented triad over a bass note when really it’s a B whole tone scale over a Bb pedal. We’re falling into a black hole. Voicing the structure and exploiting its sound within your music is what’s important, not the structure’s name.
Hindemith talks about structures and why voicings create sound and imply harmony in “The Craft of Musical Composition, Volume 1.”
Harmonic analysis is after the fact, so don’t name your chords until you’re done writing, and don’t worry if you write something that you don’t know what it is. Think of harmony as happening over time and save the play by play analysis for the classroom.