Musical simples – Under Pressure

Let’s just get Vanilla Ice out of the way first. White people and hip-hop, oy.

“Under Pressure” by Queen and David Bowie is a testament to the power of a great bass groove. The song itself is pretty weak sauce–it emerged out of studio jam sessions and it doesn’t sound like it was ever really finished. But what a bass groove!

Here’s a transcription of the bassline.

The bassline uses just two pitches, D and A. In the key of D major, these two notes are known as the root and fifth, respectively. D is the root of the D major scale, and A is the fifth note. Basslines use these two scale degrees commonly enough to have inspired this joke:

How many bass players does it take to change a light bulb?

One, five, one, five, one, five…

“Under Pressure” adds a grabby rhythm to this simple melodic framework. With basslines, less is usually more, and this one would not be improved by making it any more “interesting.”

The groove may be simple, but its relationship to the song’s chord progression is not. To make chords from a scale, pick a scale degree, and then go around the circle clockwise, skipping every other degree. The diagram below shows how you do it in D major.

If you start on D, you get the notes D, F-sharp, and A, making the I chord, D major. If you start on A, you get the notes A, C-sharp, and E, making the V chord, A major. And if you start on G, you get G, B, and D, making the IV chord, G major. Any permutation of the I, IV and V chords from a key is going to sound good, and every permutation has been used many times over. The chord progression in the “Under Pressure” groove is I-V-IV-V. This same progression can be heard in “Wonderful Tonight” by Eric Clapton, “Sweet Jane” by the Velvet Underground (sort of), the intro to “I’m All Out Of Love” by Air Supply, and many other songs.

Common though the chord progression is, the treatment of those chords in “Under Pressure” is fairly strange. Normally, the bassline spells out the roots of the chords. A typical bassline for D-A-G-D would lean heavily on the notes D, A, G, and D. But “Under Pressure” uses the same bass riff for all four chords. Under the D chord, the bass notes D and A are the root and fifth, so that makes sense. But under the A chord, the note D doesn’t make obvious sense at all, since it isn’t part of the chord, and even conflicts with it. Under G it makes a bit more sense, since D is the fifth of the G chord, but then there’s that A, which isn’t in the chord. And yet, the “Under Pressure” bassline does fit as a whole, so well that when Roger John Deacon shifts to a more conventional bass part later in the song, it’s a letdown.

The “Under Pressure” bassline is a version of a pedal tone, a single note that lies under a series of chords. Because the pedal tone repeats or drones over a long period of time, you can hold it in your memory easily, and even if it conflicts with certain chords, you don’t get confused. The “Under Pressure” riff works the same way. Because it repeats identically, it feels stable and inevitable, so even when it conflicts with the A and G chords, your mind is happy to accept it.

Using “pedal riffs” is a superbly hip songwriting strategy, and it’s more typical of jazz than rock or pop. You can hear it in Miles Davis’ arrangement of “Green Dolphin Street,” and in John Coltrane’s “Naima.” Michael Jackson was a fan of the pedal riff too. “Thriller” uses the same minor pentatonic riff throughout nearly the entire song.

The pedal riff bassline has become more common recently, because it’s a no-brainer songwriting strategy for electronic music. While it can be hard to get a human bassist to loop a riff endlessly in disregard of the chord progression, it’s the default behavior for a computer. In hip-hop and EDM, the pedal riff approach is vastly more common than a bassline that follows the chord changes (if there even are chord changes.) It’s starting to be common in film and TV music too, for example in the theme song from House Of Cards. Queen and David Bowie were just ahead of their time.