That's where we differ. I hear each chord as one sonority, not two separate halves. They seem more like upper structure chords than polychords, probably due to the omitted thirds and other important intervals. Take chord 4 and 5 (basically the same the chord moved down a whole step - just re-voiced and inverted). I've seen this chord in dozens of other scores and jazz charts (Jerry Fielding and Alex North come to mind) - and to me they're just upper structure Lydian chords. That said, it's just a different way of looking at the same thing. I'm something of a jazzhead, so I'm always going to see relatively consonant polychords like these (compared to say Stravinsky's 'Petrushka' or 'Augurs' chords or Strauss's 'Elektra' chord) as single entities, for better or worse. I agree. When I play them on the piano, it's clear that there's a jazz influence - I'd reserve a polytonal classification for situations where there are clear triads present and juxtaposed. There's enough interlocking in the first few harmonies and lack of any solid tonal identity in either "component", that is, the trumpets or trombones taken individually, for me to hear these as big extended chords. Plus, the horns sort of function as a bridge between the trumpets and trombones by sharing notes from both sections/parts, further eliminating a sense of polytonal juxtaposition. I'd analyze them as extended/added-tone (I tend towards the latter) chords, with respect to the top note, taking that as a sort of melody that is harmonized in a Debussyian kind of way, by seeing what triads can be formed by changing around the voicings. Sooo doing that, I find that... Chord 1 is a Bb minor with an added 4th and 2nd Chord 2 is an F7 with an added 4th Chord 3 is sort of a BM7 without a 3rd Chord 4 is an Ab major with an added 4th Chord 5 is an Ebm7 Chord 6 is a DbM7 major with an added #4th Chord 7 is a G major with added 2nd and 6th Chord 8 is the only one that feels like it could be polytonal in its original voicing, but I'd probably still call it a DbM7 with added augmented 5th, especially since the other parts then resolve it to a clear Db realm Keeping the melody line and bass line (whether that gives an inversion or an added-tone in the bass) both intact, that makes sense to me. Now, analyze that progression as you will... Db with chromatic excursions?