Why do a 1, 3, and sharp 4 work well in this piece?

Question

I recently came across a short piece which I decided to try and analyze, but I have some questions about it. I am still a bit new to music theory but if I'm correct, most instances of non-diatonic notes/chords are instances of secondary dominants or borrowing from the parallel minor key.

However, measure 21 confuses me. In the measures leading up to it, E and C are played with a "bass note" which steps down chromatically from A to Ab (or is it G#) then to G then to Gb. The way I interpret this is using a vi chord, then the Ab is borrowed from the minor key in the context of the very common iv chord, then we have the I chord, then this mysterious Gb/F# shows up.

Thus my question: Why does this sharp 4, then followed by a 3, sharp 4, and a 1 work well? Is it just the chromaticism set up by the previous measures, or is there more going on? Maybe something lydian related?

Also, on more than one occasion, the song uses the notes Bb, E, and G to form what I believe is a diminished chord. It is then followed by the V/ii, as in measures 5-6 and 12-14. Again, chromaticism supports the Bb in the previous measures.

In short: What is "going on" with 1-3-#4 and 3-5-b7 chords in a major key? Why do they work well? Also, do you know of any other pieces which have these?

Answer 1

First you should be aware that there is a glaring error in this transcription. Either there is a beat missing in bar 10 or bar 10 should be a 3/4 bar because beat 4 of bar 10 and every other bar after that is actually a downbeat. It is apparent by the phrasing of the melody. Play the midi file with the play button and you will see that every 4th beat starting at bar 10 sounds like a downbeat.

Taking that into account beat 4 of bar 21 and the first 3 beats of bar 22 are actually the same bar with the F# being the downbeat. This is an F#m7b5 chord (with an added 9th) which transitions beautifully to a C/G because of the half step motion up in the bass and the E common tone in both chords. The #IVm7b5 is a very colorful chord often used by jazz players as a substitute for a ii or IV chord and usually to start a descending pattern but in this case it is used to ascend to the I chord with the 5th in the bass.

Leading up to that I agree with your analysivi on bar 18/19 but the following 2 bars I hear as G#+ then C/G and finally the F#m7b5, a fairly common and effective chromatic descending pattern.

The other thing you mentioned the Bb E G does have the makeup of a diminished chord. It is part of a progression with a chromatic descending bass line under a common tone of G: C G/B Eo/Bb A7 then Dm.

As a postscript I would like to add the the G#’s in bars 9 and 10 should be Ab’s since this is clearly a IVm or Fm chord.