How should this half-diminished seventh chord from "Christmas Time Is Here" be analyzed in terms of its harmonic function? [duplicate]

Hi everyone.

I'm working on an analysis of Christmas Time Is Here, which is in F major.

I'm trying to determine the best way to analyze the Bm7(♭5) chord circled in the image. I have 3 explanations right now:

1. It is a viiø/V resolving (after moving through the B♭m7 passing chord) to iii7, which is the relative minor substitute for V.
2. It is a ♯ivø7 chord borrowed from F-Lydian.
3. It is a iiø7/iii or a ivadd6/iii, tonicizing A minor.

Do any of these seem to be the best way to go about analyzing the chord? Is there a better way of analyzing it that I haven't included? I'd love to read some thoughts on how to explain the function of this chord in the music. Thanks in advance, and happy holidays!

• In conjunction with Richard's answer I would be most inclined towards your 3., that is, it is introducing a move to A minor whilst also generating this downward parallel movement back to the cadence Nov 28, 2020 at 23:41
• You asked this same question a year ago, and the same two people responded: music.stackexchange.com/questions/92632/… Nov 29, 2020 at 2:07
• Yeah, I only asked again to see if there were any different interpretations that I didn't read when I asked it last year, and I wanted to see if people agreed with any of my analyses of the chord. I can close the original. Nov 29, 2020 at 4:26
• @Peter I knew this question seemed familiar, but I never would have dreamed it would have been such an exact duplicate. Thanks for pointing this out! Nov 29, 2020 at 15:45

I see and jazz musicians use the #IVm7b5 (Bm7b5) mostly in one of two ways:

1. It can be a non-diatonic substitution/reharmonizaion for the diatonic IVmaj7 (Bbmaj7) chord or iim9 (Gm9) chord. It has 3 notes in common with each of these two chords, D F and A giving it a somewhat subdominant quality despite the tritone it contains. For example, the last 8 bars of the song “Emily” starts on a iim7 but many jazz players use this #4 chord as a substitution in that tune.

2. It is also commonly used as the beginning of a cycle of fifths descending progression which ultimately leads to the tonic: B-E-A-D-G-C-F. These chords can be 2-5’s or all dominants or any combination of the two. Any of these chords can be replaced with a tritone substitution which would make for a chromatic descending progression, which is mostly the case here. The Bm7b5 functions like the 2 of a 2-5 to the iii chord in these cases even though in this song there is a chromatic m7 chord instead of a dominant going to the Am7.

In the case of this song, it actually is a bit of both. You can replace the Bm7b5 with either a Gm9 or a Bbmaj7 and the harmonic flow would not change all that much. It also uses a combination of cycle of 5ths and descending chromatic chords to go from B to F.

Some other examples of this usage are the second 8 bars of “Night and Day” and the second 8 bars of “All God’s Children Got Rhythm”.

• So are you saying that "Dm6/B" interpretation is plausible only if it's used in a circle-of-fifths motion like a series of 2-5's? I think the Bm7-5 chord can be replaced even with a plain regular Dm in this song and it will pretty much the same thing. Just slightly less special flavor and the bass motion to Bbm gets bigger. Nov 29, 2020 at 10:50
• @piiperiReinstateMonica Whoa, where did I say that? I gave two different examples of how the chord is “mostly” used. There are many other less common way it can be used, for example, leading to a tonic chord in second inversion (Bm7b5-F/C) or even as an ambiguous tonic chord as in the first chord of “Inner Urge” by Joe Henderson. The Dm you mentioned would work, in the 5th bar of “Polka Dots and Moonbeams” in the key of F, either a Dm or a Bm7b5 are played by jazz musicians and is one of those spots you listen out for when faking the tune with guys you have never played with. Nov 29, 2020 at 19:01
• @piiperiReinstateMonica I see you prefer the spelling of Dm6/B as do many others. I know the history of how Dizzy and Monk used to call it that. However I prefer the m7b5 label for 2 reasons. First, almost every time Dizzy or Monk used that chord it was as part of a 2-5 in minor (A Night in Tunisia, Round Midnight) so the m7b5 spelling makes more sense as a 2-5. Secondly, is it’s a root position 7th chord. Whenever possible I like to spell a chord from the root as opposed to as an inversion because it makes it easier to see the function, especially when reading, playing and improvising. Nov 29, 2020 at 19:16
• I was just reading your description and trying to see which of the two categories would fit the "modified vi" interpretation, which to me feels the most natural one just by playing and listening. I'm a bit reluctant to use the "m7-5" notation, because when used in pop lead sheets for non-jazz players it tends to be played as a regular m7, which often breaks the harmony progression and clashes with the melody. And because that's how I first learned to know the chord as a kid - as a m6 but with the six in the bass, giving the added bonus of a fourths/fifths bass movement in a 2-5 sort of way. Nov 29, 2020 at 19:59
• @piiperiReinstateMonica I am a BIG fan of m6 chords but more in first inversion and mostly as a i or a iv chord. It just doesn’t sound like a m6 chord to me once you move the 6th to the bass. Maybe it’s because I’m primarily a bass player and play and analyze everything from the bottom up. Hearing and analyzing it as a vi is legitimate and justifiable, things can be interpreted in different ways. As for your reluctance to use it in notation, a musician that knows chord symbols should know that chord and not playing the b5 is simply a mistake, like playing a C7 instead of a Cmaj7. Nov 29, 2020 at 20:18

I would argue that it's the beginning of a larger pattern of chromatically descending seventh chords. Notice that this Bø7 moves to a B♭m7, and this B♭m7 then moves through m7 chords built on A, A♭, and finally G, this last chord being the ii7 of the tonic F.

We call this—when a chord shape is moved up or down in tonal space—planing. And although the planing isn't exact beginning with this Bø7 (if it were exact, it would have an F♯ to make it a m7 chord like the successive harmonies), I think it's significant that the "wrong" pitch, F, is the tonic of the entire excerpt.

Ultimately, I'm not sure it's helpful to give a Roman numeral to this chord, Instead, I think it's best to view this Bø7 as beginning a prolonged sequential move to the ii7 that sets up the cadence on the Fmaj9.

• Thanks very much for this answer. I agree that analyzing this as a planing progression might be the best option. Maybe mixed planing since it isn't completely diatonic planing nor real planing. Very interesting how smooth it sounds. I need to explore jazz harmony more! Nov 30, 2020 at 13:42

It starts off a 'cycle of 5ths' sequence leading to the tonic with half the chords being ♭5 substitutions. Without substitutions the roots would be B, E, A, D, G, C, F. A very common harmonic cliche, with or without the substitutions.

• This definitely makes sense, thanks for this answer! Nov 30, 2020 at 13:43

I see the Bm7-5 chord as a variation of Dm or Dm6. If you want Roman numerals, it would be something like vi6/IV#. Try playing this expanded three-step sequence in place of the Bm7-5: Dm - Dm/C - Dm/B. But the song skips straight into Dm/B which is really the same thing as Bm7-5. And then it goes to Bbm.

Sometimes that chord is used towards the end of a longer progression, and then you could do for example ... Bm7-5 (=Dm6/B) - F/C - C7 - F. Or something like Bm7-5 - C7/Bb - F/A - Abdim - Gm7 - F.

Edit. If we should look at all possible uses of the chord, not only this song, then how to see a Bm7-5 depends on where you're coming from, or maybe where you're trying to move the harmony with it. A chord is a sum of its parts, and all interpretations are possible at the same time. If there's a B note, it allows for a half-step motion to Bb or C, or a fifths motion to E.

If we're in the key of F (expecting to eventually get home to F), and the previous chord is Gm9, then Bm7-5 is better seen as G9/B - a bass movement of a third, and a temporary modal mixing of D Dorian into the picture.

• I agree with a lot of this, especially the reference to temporary modal mixing of D Dorian (F Lydian). Thanks for the answer! Nov 30, 2020 at 13:46