Can you please explain the role of that Em7b5 in the following jazz progression in terms of functional harmony?
| Cm7 | Em7b5 | Bbmaj7 | G7 |
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Even in tonal music every chord does not need to have a functional role.
Beside the possibility of mixing tonal and non-functional harmony, the obvious case would be a passing chord.
| Cm7 | Em7b5 | Bbmaj7 | G7 |
In that progression
Bbmaj7 combine to give all tones for
Bb major, the
G7 could also be a clear secondary dominant to the
Cm7. Without any other details about what this music does, it set's up a very clear possibility for
Bb major as the tonic. Nominally it could be...
| Cm7 | Em7b5 | Bbmaj7 | G7 | | Bb: ii7 | p.c. | IM7 | V7/ii |
...I say 'nominally' because you don't have a dominant for
You could add the dominant with something like this...
| Cm7 | Em7b5 | Bbmaj7 | G7 | Cm7 | F7 | Bbmaj7 | Bb: ii7 | p.c. | IM7 | V7/ii | ii7 | V7 | IM7
...I only add the dominant, because your question is posed in terms of functional harmony, and I wanted to complete the picture how what you already have could be emphatically functioning in
Bb. Of course harmony does not need to be functional, but to the extent that it is, the dominant is critical for establishing tonality. Adding a dominant (to a tonic, not a secondary dominant) makes the functions clear.
p.c. above means passing chord.
...in terms of functional harmony?
In functional harmony, secondary functions, need to be backed up with some kind of analysis that the purported secondary function is actually fulfilled.
Em7b5 is supposed to be either
viiø7 - or the theoretical incomplete
F major, or
D minor, something of either function needs to actually be in the music. The next actual chord is
Bbmaj7, which is
F major or
So, that would give us a dominant to subdominant in
F major or subdominant to submediant in
D minor. In terms of functional harmony, both are dubious. At best you might call the first some sort of deceptive move and the second pre-dominant movement that never actually moves to it's related dominant.
I think your four chords hint at the possibility of
Bb major, but the
Em7b5 doesn't seem to have a function to that tonic or convincingly to another. That is not a problem. You can voice the chords so that
Bbmaj7 in all step-wise motion and consider it a passing chord.
Your function does not fall right into clear tonal function. It's ambiguous. That's why every answer so far gives you completely different analysis. Calling it ambiguous isn't a diagnosis, it's just a description. Unless your purpose is to revise it for clear function, there's nothing to "fix." Although, if you want to embrace ambiguous, non-functional harmony, I'd say don't get hung up on functional analysis. Why do functional analysis if you don't care about function harmony? Look to other musical elements to assess what you're doing.
EDIT to elaborate on comments:
To understand functional harmony you need to understand dominant harmony and to understand dominant harmony you need to understand how the leading tone and subdominant work. I like to do that in solfege and will use that below.
Dominant function at its essence is leading tone
TI moving to up tonic
DO and subdominant
FA moving down to mediant
FA are the tones that define a dominant chord. Labeled as chord tones
FA are respectively the major third and minor seventh of a dominant chord. This is true in the "classical" style and jazz too.
When tones are altered from diatonic they tend to move in the direction of the alteration. So, for example a tone that is altered by raising it tends to move up a step as its next move. In practical, functional terms, this means raised tones often become new leading tones and lowered tones often act as new subdominants and involve either a modulation or a tonicization. If an altered tone does not act in that functional way, it may be reasonable to then consider the altered tone a chromatic passing tone.
The term passing is applied to a tone or tones that do not belong to a proper chord. In the nomenclature of non-chord tones passing is applied when the case is specifically all the tones involved moving by step in the same direction. Example, in a
C major chord, with melodic motion of
C D E the
D does not belong to the
C major chord, but "passes" between chord tones
E with the whole passage being steps in the same direction.
More than one tone could be involved with a passing motion. The commonest example is the passing 6/4 chord. Example, in
C: I6 V6/4 I the
V6/4 is considered dissonant, an "improper" chord, with the impropriety being the
D in the bass. If the voice leading is such that the bass part is
E D C the then
D is a passing tone between the chords tones
I, and the whole chord is referred to as a passing chord.
"Passing" can be applied generally to anything, even entire passages of harmony, that are regarded as unessential to the principle harmonic structure.
Back to the functional analysis.
Bb major we have this essential functional movement of the subdominant...
In my analysis of
Bb major, and the other answers of
C minor, either key treats the
Eb as a diatonic tone, therefore the
E natural of the second chord is an altered tone. With the tendency of raised altered tones to move up that results in
E natural becoming a new leading tone tonicizing the dominant...
...tonicizing means that the tone
F which is regarded as the dominant scale degree,
Bb changes to the tonic scale degree,
F. Temporary shifting of the tonic like this is normal in functional harmony.
Even in the case of analyzing the progression in
C minor, the alteration of of
E natural would still tend to move up to
F, where the
E natural again becomes a leading tone, but this time to the subdominant.
E natural could be emphatically harmonized with dominant harmony in a
I'll continue looking at it in
Let's now look at how you could harmonize
Bb major, in functional terms, either as unaltered
Eb or altered
Eb is the subdominant
FA which in a dominant chord will move down to the mediant
MI of a tonic chord...
E natural acting in a functional way is the new leading tone
TI which in a dominant chord will move up to the tonic
DO of a new tonicized chord...
Those two examples are just the basic functional expectation of
E natural in
Your actual progression does something else. The
E natural is the root of a half diminished chord.
It is possible to regard that half diminished chord as an incomplete
C9 chord where the
E natural is the chord's third. But, in that case the tonic it implies is
However, the next chord is not a
F chord. It's a
Bb chord. You could call it a retrogression or a deceptive progression, but suffice to say it is not progressing in the conventional functional way. As stated before we can then regard the
E natural as not a functional tone of a dominant chord, but as a chromatic passing tone.
If we voice the whole chord so that all tones are moving in smooth voice leading step, the entire chord can be regarded as a passing chord.
I have to admit that it's easier for me to think of the Em7♭5 as a voice leading construct, as Cm7 - Em7♭5 only requires shifting the Cm7's C and E♭ one step each and leaving its G and B♭ as is, and Em7♭5 - B♭maj7 only requires shifting the Em7♭5's E and G one step each and leaving its B♭ and D as is.
With that being said, there are at least two ways of trying to fit that Em7♭5 into functional harmony.
Aaron's answer partially alludes to Em7♭5 being a tritone substitution of V7/iv or a rootless version of V9/iv. Tritone substitution involves keeping a tritone in the chord you want to modify, changing at least one other note, and expecting the tritone to resolve the same way (barring enharmonic re-spellings) in both chords.
We can also think of Em7♭5 as (♮)viø7/v, so Cm7 - Em7♭5 - B♭maj7 - G7 can be interpreted as i7 - (♮)viø7/v - III7/v = VII7 - V7.
The Em7b5 here is functioning as a substitute for C9 — that is, it's as though the music shifted from C minor to C major. The C is established as the tonic by the first chord, so the ear will retain it and hear the E chord in that context. Thus in functional harmony terms, the progression would be
i | I | VII | V .
(Cm9) (C9) Cm7 Eb7b5 (D) D Bb Bb G G Eb E C (C)
A similar relationship — an implied minor-to-major shift — exists between the following two chords. Consider that BbM7 contains the upper notes of Gm9.
(Gm9) (G9) BbM7 G7 A (A) F F D D Bb B (G) G
In that light, the entire progression can be viewed as:
i | I | v | V or
i9 | I9 | v9 | V9
| Cm7 | Em7b5 | Bbmaj7 | G7 |
The Em7b5 works as a secondary dominant in the sense that it makes you expect an F something chord, the E note sounds like a leading tone heading to F. But instead of an F based chord, the progression gives you a Bb chord. So a secondary dominant function doesn't really get fulfilled, the desire and wanting is interrupted. But when reasoning about what's happening in the progression, it's good to know the "what could have happened" and what expectations the chords created in your mind along the way.
Do you feel that the home chord is C minor, or maybe G minor? Or Bb major? What's the key in your opinion? To me the Bb being a maj7 makes it sound like it's more in Gm or Bb than in Cm.
You could respell the Em7b5 as C9/E. Which could be simplified as C7/E. Or even just C/E. Or just a plain E note without anything else, given this context.
To try and feel how the secondary dominant would have worked, had there been the F chord. How would this sound like to you:
| Cm7 | C9/E | F7 | Bbmaj7 |
Now you're in Bb major. Or I am at least, YMMV.
But back to the original progression, the G7 could be a secondary dominant going back to Cm7, if you think the real key is Gm or Bb. Or if you feel the real key is Cm, then the G7 would be Cm's dominant. But nevertheless, the Em7b5 still works as a potential secondary dominant in all interpretations, in the sense of creating expectations.
I'd actually take a completely different take than the other answers here. The sequence
Cm7 | Em7b5 | BbMaj7 | G7
Is likely a root of Eb progression. Cm7 is VI, BbMaj7 is V (though Maj7 chords are frequently IV) and Em7b5 is likely a tritone substitution for BbMaj7. A more clear example is the a
II V I in the key of Eb, with Cm7 serving as a substitute of Fm7. A more commonly extended version of
II V I is
III VI II V I. Keeping this assumption in mind, Em7b5 is substitute for II (which is a flat II in key of Eb). It's difficult to ascertain which is the intention without looking at the key the melody is playing in.
Since the question asked about the Em7b5, the G7 was mostly ignored but I doubt that will change the options here. If the 4 chord progression is repeated as written above, then it's clearly
III VI II V (I) without resolving the root if the composer wanted to make some artistic substitutions (flat II substituting II, dominant III replacing III, Maj7 replacing dominant on V) but it's difficult to give a decisive answer without the key or surrounding chords. But the answer fundamentally boils down to it being an embellishment; a substitution for an otherwise standard chord.
After thinking about it for a while, there is another common progression that this does follow (Rock/Alternative/Fusion progression)
VI IV V III. The entire explanation above is the same (same key and same replacements for the standard chords) but the Em7b5 is a substitution for IV. This explanation doesn't require much of an intuitive leap as
(III) VI II V repeated as the bar starts on the correct measure instead of one measure behind. So now it will be `VI bIIm7b5 VMaj7 III7, with bIIm7b5 substituting IV, VMaj7 substituting the common V7 and III7 substituting the common IIIm7.