Asaf Peres

Calvin Harris and Dua Lipa's "One Kiss" is Ambiguous AF

Tonal ambiguity is pretty common in pop music. I know quite a few songs that can easily be heard in their relative major or minor. What I’ve never encountered, though, is ambiguity between different key signatures in a song that is on paper entirely diatonic to one key.
In comes the new Calvin Harris and Dua Lipa collab:
“One Kiss” (written by Harris, Lipa, and Jessie Reyez) is in the key of F major, at least according to the official sheet music published by EMI, which places a Bb in the key signature. Yet I hear it as being in the key of A minor, and to be honest I can’t imagine anyone hearing it differently.
Maybe it’s a Laurel/Yanny thing, which would be fitting given the ambiguity of Lipa’s 'reserved passion' in this song.
On paper, there is no reason to question the official key: The seven-note collection used in this song spells F major; the chords exclusively use these seven notes as well; and the vocal melody falls in line, or at least does not contradict F major. On its face, there is nothing in the sheet music that would lead one to believe that this song is in any key other than F major.

But every time the chords loop back to Am I hear it as the tonic chord. And when Lipa sings “One kiss is all it takes” in the chorus I hear these scale degrees:
NOT these scale degrees:
​But someone decided that this song is in F major. It could be the songwriters (Lipa, Adam Wiles, Jessie Reyez), Harris, the person who produced the sheet music for EMI, or all of them unanimously.

Even the Wikipedia article lists this song as in F major:
Screenshot taken on May 21, 2018
​It’s possible that some of the people responsible for creating this song and disseminating the public information about it did so without really thinking about it too much and just went with what seemed to be obvious on paper, but I assume that at least one or two people in that chain listened carefully and thought it through before deciding on F major.
And to be clear, I’m not saying they are necessarily wrong. Harris, Lipa, and the EMI people may read this one day and think that I’m a moron for even suggesting that “One Kiss” could be in anything other than F major. You may even think so too, and that’s fine. But from my perspective this is something worth exploring, so here is my defense of hearing this song in A minor.

​The Makeup of the Chords

I think the most important (and most interesting) reason for my hearing “One Kiss” in A minor lies in how the chords are constructed. Harris does something similar to what he did in his 2011 collab with Rihanna, “We Found Love” (I assume this was Harris’s doing because of this similarity): The bass line implies diatonic, root position triads, but the upper voices are made up of a repetitive keyboard riff that doesn’t quite follow the implied harmony. Instead, it colors the chords and makes the progression somewhat more ambiguous:

​The bass motion is A-Bb-F-G. Assuming each bass note initially implies a root position triad in F major, here is how the keyboard riff transforms the chords:
Am  remains  Am
Bb becomes Bbmajor7
F becomes Fmajor7

So far these are not substantial changes in terms of determining the tonal center and quality of the key. But here is the really significant one:
Gm became G7sus2

(sus2 is the commonly used representation of chords in which 2 replaces 3 in a root position chord, even when it doesn’t behave like a traditional suspension)
As with the previous chords, the added 7th doesn’t change much, but what makes this last chord so important is the sus2.

(Note: from this point forward, for the sake of clarity and brevity, I will ignore the sevenths of these chords.)
The official sheet music lists the last chord in the loop as Gm9. However, the note Bb, which would be responsible for the minorness of this chord, is not actually present in this sonority. Even in sections of the song where the makeup and/or the order of the chords is slightly changed, there is still no Bb over the bass note G: In the bridge (2:35–3:07) the sus2 turns into a sus4 (which, like the sus2, is not an actual suspension and therefore does not resolve to Bb); In the postchorus (1:18–1:34 for example) we only hear the bass note G as a passing note with no upper voices.
In other words, the sus2 and sus4 neutralize the minorness of the chord we hear over the bass note G, making it possible to hear it as an unrealized major chord.
Combine this with the fact that the chord Am is on the strongest hyperbeat of this chord loop (and even in the bridge it’s on the third hyperbeat, which is still a strong hyperbeat) and just like that, the bass motion F-G-A that’s embedded within the loop starts to sound a lot like VI–VII–i in A minor rather than I–ii–iii in F major.
And this is important because VI–VII–i is an extremely common progression in pop music and is strongly associated with its final chord being the tonic chord of a minor key. In a genre that has significantly weakened the role of functional harmony and has all but done away with common practice cadences, the VI–VII–i progression is as close to a cadence as you will find, in the sense that it reinforces the ‘tonicness’ of i. So if you hear this F-G-A bass motion as representing VI–VII–i (which I do), it’s hard not to hear this song in A minor.

​The Other Side of the Story

In order to make the case for “One Kiss” being in A minor, I need to acknowledge and address the elephant in the room:  the presence of a B-flat chord and the absence of any B-natural in this song. So here it is:
Although I said that the F–G–A bass motion represents a VI–VII–i in A minor to my ears, I should acknowledge that the Bb–F motion sounds a lot like a pseudo plagal cadence (a cadential IV–I motion, as opposed to the more prevalent V–I). In fact, this is even strengthened if we consider the previous chord, making it an Am–Bb–F chord progression—If we call the IV chord in a plagal cadence an ‘alternative dominant’ then a iii that precedes can be heard as an ‘alternative predominant’ because it provides the up-by-step bass motion that precedes the cadence. Just like the aforementioned VI–VII–i, the progression iii–IV–I (or III–iv–I, or in some cases I6–IV–I) is also a common pseudo-cadential move. You can hear it, for example, as part of the chord loop of the chorus in Taylor Swift’s “Ready for It”, or in Tove Lo’s “Timebomb” (1:12–1:25), where it forms a rare complete cadence that reaches a resting point on the tonic, both harmonically and melodically. 

Which is the True Tonic?

​This is truly interesting—There are only four chords (with occasional minor changes in their makeup and order) that loop throughout the song. Yet, this seemingly diatonic and simple loop contains two competing pseudo-cadential progressions and constantly tick-tocks between the two possible tonal centers. So which one wins out?
Is it this one?

Or this one?
​Personally, I can only hear the latter, just like I can only hear Laurel and can only see white and gold.
While on paper, the F major plagal cadence should clearly take precedence, I hear the Bb–F motion not as an actual cadence, but as a plagal tonicization of F.
What does that mean? Tonicization is when you momentarily make a non-tonic chord sound like a tonic by creating tonal gravity toward it. Unlike a modulation, in which the music establishes a new tonal center and stays on it for a substantial period of time, a tonicization is brief and the music immediately adjusts back to the real tonal center.

​Although the B-flat never adjusts to B-natural, the sus2 alteration of the G chord allows us to complete the missing information in our brain and actively adjust it for ourselves, especially since the Am chord falls on the strongest hyperbeat almost throughout the song. 

The Vocal Melody

​Had I only heard the chord progression without the vocals, I believe I would still hear it in A minor, but I would also be able to hear it in F major if I really tried. However, the vocal melody seals the deal for me.
The main thing about it is that aside from a few touches on F as a passing note in the verse, Lipa’s melody throughout the song sticks to the five notes that make up the A minor pentatonic scale. And although I mentioned that the vocal melody does not contradict F major, it also does nothing to confirm it. Lipa sings neither B-flat nor B-natural, and seems to purposefully avoid any tonal closure. 

Final Experiment

None of the above points on their own would ‘transform’ a song from F major to A minor: Just because a chord is on the strong hyperbeat doesn’t make it the tonic; the F-G-A bass motion could easily exist as I-ii-iii in F major; and a note doesn’t need to be heard in every part of the texture in order to ‘count’.
But while I don’t have a single decisive ‘on paper’ winning argument, my ears have decided for me that “One Kiss” is in A minor, and the combination of the factors I laid out in this article suggests that I might not be crazy. 
Just to be sure, I decided to conduct one more experiment—I created several new chord progressions that are firmly in F major and ones that are firmly in A minor and played Lipa’s vocal melody over each of them. I may be biased, but this experiment certainly confirmed my initial hearing. Singing the melody over the A minor progressions sounded very similar to what I hear in the original song, while trying to sing it over the F major progressions sounded different and awkward, despite there not being harsh dissonant clashes.
I also tried to change the Gsus2 chord to Gm, and I still heard the song in A minor–The Gm chord just sounded out of place, although I must admit that changing it to a G-major chord still sounded strange. For whatever reason the sus2 sonority feels by far the most fitting.
So there you have it. I’m in the A minor camp and cannot imagine this song being heard in any other key.

​If you hear otherwise, or if you have more conclusive reasoning one way or another, I would love to hear from you, either in the comments below, on my Facebook page, or via email.
Wait---What About A Phrygian?
One last thing–I’m quite sure that at some point someone will suggest to me that maybe I should hear this song in A Phrygian, agreeing that A sounds like the tonal center but that the presence of Bb transforms the minor (Aeolian) mode into Phrygian.
So to address this point: Technically, this could be a valid way of viewing the modal makeup of this song. However, Phrygian mode implies that the Bb would be an upper leading tone to the tonic (A), and since the Bb in “one Kiss” does not behave this way but instead tonicizes F, I don’t think the tonal behavior of this song would be accurately represented by the Phrygian mode.

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