Led Zeppelin and the folkloric integrity of the blues

There is a fascinating moment in “When The Levee Breaks” by Led Zeppelin where Robert Plant plays a very flat ninth on the harmonica. I love this note, because there is so much music theory and history encoded within it. Listen at 0:41.

Before we can get into the details of this note and what makes it so, um, noteworthy, you need some background. “When The Levee Breaks” is heavily adapted from a song of the same name by Memphis Minnie and Kansas Joe McCoy. It tells the story of the Great Mississippi Flood of 1927, which left hundreds of thousands of mostly Black people in horrific refugee camps. Kansas Joe sings and plays rhythm guitar, and Minnie plays lead.

Led Zeppelin’s song is a word salad of the original over a different instrumental backing. The lyrics don’t make any particular sense, and they don’t try to; Robert Plant is going for more of a vibe. When I was a teenaged Zeppelin fan, I didn’t know what a levee was, and my understanding of Black history was vague at best. I certainly didn’t know anything about the Great Mississippi Flood. The same was probably true of Robert Plant when he wrote his lyrics.

Led Zeppelin is (in)famous for reworking old blues and folk songs, sometimes with attribution, sometimes without. (There’s an entire Wikipedia page about this!) The band credited Memphis Minnie for “When The Levee Breaks”, but not Kansas Joe McCoy. Jimmy Page liked to mix existing blues riffs with his own ideas, and Robert Plant used a similarly collage-like process for lyrics. They have taken a lot of heat over the years for this practice. You could argue that they were just following in blues tradition; Robert Johnson and Howlin’ Wolf also wrote songs by collaging together fragments of existing songs. However, you could also argue that when Howlin’ Wolf uses this shared musical property, it means something very different than when a white British guy does it. Led Zeppelin did sincerely love the blues, but love and theft have a way of going together.

Anyway, I’m more interested in the musical aspect of “When The Levee Breaks” than the lyrics. Here’s my transcription of the first chorus of the Memphis Minnie/Kansas Joe McCoy original. The notes in blue are blue notes between D-flat and D; I explain those in depth below.

Here’s my transcription of the main groove from the Zeppelin version. The recording sounds in F, but it was written and recorded in the more slide-guitar-friendly key of G and then slowed down (and thus lowered in pitch).

In the rest of the post, I’ll talk about the song as if it’s in G. If you want to play along with the recording, just transpose everything down a whole step.

Robert Plant is playing a C harmonica, which, when you draw (inhale) on it, produces a G9 chord. Here’s a blues harmonica explainer. The important thing to know is that you often want to bend your drawn notes, meaning that you intentionally make them go flat. This enables you to play notes from the blues scale, and also the blue notes in between the piano keys. On your C harmonica, you can bend G part or all of the way down to F; you can bend B part or all of the way down to A; you can bend D part or all of the way down to C; and you can bend F part or all of the way down to E. You could also bend A down to A-flat, which is what Robert Plant does in his solo. However, the old blues guys did not generally do this. They might have put a little color on that A, but they didn’t do deep bends on it.

But why do harmonica players bend their notes in the first place? Blue notes are a profound music-theoretic mystery. Why should it sound good to play certain notes so far out of tune? Performers in every kind of Western music inflect their pitches for emphasis and feeling, but outside of the blues and its descendants, no one intentionally plays notes that are a quarter-tone flat on purpose. It’s customary to explain blue notes by saying that they are harsh, weird, or dissonant. But this is not the way I and other blues lovers experience the music. Blue notes sound unusual and ear-grabbing, but they don’t sound “bad” the way that an extremely flat note would in a performance of, say, Mozart. How can this be?

A better explanation is that the blues is not a system of discrete pitches. Instead, it’s a system of flexible pitch zones. Blues musicians use three main pitch zones: the one between 2^ and 3^ (A and B in the key of G), the one between 4^ and 5^ (C and D in the key of G), and the one between 6^ and b7^ or a little past it (E and F in the key of G). The corollary to this idea is that the various “blues scales” are 12-TET approximations of the pitch zones, a simplified version of them that you can play on the piano and express in standard notation. Here’s a great series of explainer videos on the subject:

The pitch zone idea is accurate as far as it goes. But it raises another question: why do blues musicians use those pitch zones and not others? For example, you hardly ever hear a blues musician play a pitch between 3^ and 4^, even though they are constantly exploring the regions below 3^ and above 4^. Another question: can you use any arbitrary pitch within the zones, or are there specific spots to aim for? Unfortunately, there is not much hard data on these questions. Jeff Titon’s excellent book about country blues includes plenty of blue note analysis, but he identifies microtonal pitches by ear. There have been a couple of more recent studies that use computers to identify pitches more empirically, but they have been small and not very systematic. Few music theorists even acknowledge that blue notes exist, much less offer explanations of them.

Fortunately, ethnomusicology has some wisdom to offer. Gerhard Kubik has a theory that blue notes originate in traditional West African tuning systems based on the natural overtones of 1^ and 4^ (G and C in the key of G.)

This theory is impossible to prove. There was a lot of time between enslaved West Africans arriving in the Americas and the first recordings of the blues. Nevertheless, I find it convincing. When I play the guitar or harmonica and bend notes, there are a couple of sweet spots within the pitch zones: a bit below and above b3^, a bit below 3^, midway between 4^ and #4^, a bit above #4^, and a bit below and above b7^. These sweet spots align exactly with the seven-limit just intonation intervals that Kubik identifies in certain West African traditions. I have put a “just intonation blues scale” into MTS-ESP and played guitar over it, and it’s remarkable how good it sounds.

I believe that the flexible pitch zones we have now are the result of enslaved Africans searching around with their voices and instruments for harmonics-based intervals from their cultural memory. That searching became an important expressive dimension of the music. Over time, the memory of African tuning systems faded and the sound of searching across the pitch zone became the sound of the blues.

Whenever I talk about this, someone always responds, “Yeah, but Ethan, no one was using oscilloscopes or calculating pitch ratios in the Mississippi Delta.” True! However, it’s easy to discover the harmonic series of the guitar’s E and A strings just by hacking around. You can find the first seven overtones without much trouble, and if it’s quiet and you listen closely, you can hear the ninth and eleventh overtones too. Harmonics are not an advanced or esoteric concept for guitarists; we routinely use the third, fourth and fifth harmonics for tuning by ear. There is also reason to believe that Black American vocal tradition uses harmonics-based tuning; for example, the famous “barbershop seventh” is a dominant seventh chord tuned to harmonics four, five, six and seven.

Enthusiastic though I am about Kubik’s theory, you should remain skeptical. This might all be a coincidence! There may never have been a blues musician who knew or cared about just intonation. Maybe it’s colonialist of me to assume that there must be some Pythagorean math behind the blues. Maybe blue notes have no logical explanation at all. I find Kubik convincing, but I wanted to be convinced, because the idea appeals to me aesthetically. If someone has more evidence for or against the theory, I want to hear it. The thing to remember is that the blues evolved through centuries of aural tradition, and for a lot of that time, Black Americans weren’t even legally allowed to read or write, so we will probably never know for sure.

Rock is famously descended from the blues, but they have important stylistic differences. Like all folk musics, the blues is conservative. There is a narrow and specific palette of melodic and harmonic ideas that register as “bluesy.” This is why you can easily identify a blues song as a blues song. Rock uses a much wider vocabulary. For example, rock musicians will bend any chromatic pitch by any amount. This is where we come back around to Robert Plant’s harmonica solo. When he bends 2^ down toward b2^, he is not inside one of the traditional blues pitch zones. Maybe the note sounds so weird because there is no nice seven-limit just intonation interval between b2^ and 2^, or maybe the note sounds weird because it simply isn’t traditional, but either way, it sounds weird.

I can easily imagine what was happening in Robert Plant’s head during the recording session. His blues heroes all bent their notes, so he was bending his notes. As he was running up the drawn notes, he overshot F and landed on A instead. He tried bending it, and thought, huh, that sounds cool, I’ll lean into it. He’s right! It does sound cool. It just isn’t the sound of the blues. This is a perfect microcosm of Led Zeppelin’s general approach. The blues is a point of departure for their music, not a tradition they were trying to preserve. Like his lyrics, Robert Plant’s harmonica playing makes reasonably effective use of blues tropes, but it doesn’t have what Ethan Iverson would call “folkloric integrity“.

Is Led Zeppelin a good blues band? They are a great rock band, one of the greatest. But their blues playing is not necessarily “good” by the standards of the blues. I don’t believe that you always have to be reverent toward blues tradition. All my favorite jazz musicians extended and abstracted the blues in ways that managed to break new ground while maintaining folkloric integrity: Duke Ellington, Thelonious Monk, John and Alice Coltrane, Charles Mingus, the list goes on. By contrast, Zeppelin’s bluesy material tends to evoke this excruciating scene from Ghost World.

I do genuinely love “When The Levee Breaks” in spite of everything. However, I love it as a track more than I love it as a song. During my audio engineering education, I learned just how much musical heavy lifting is being done by Jimmy Page’s production. Led Zeppelin records represent the absolute cutting edge of their era’s studio technology, and the tracks sound so futuristic and cool that it’s easy to overlook their underlying goofiness as songs. “When The Levee Breaks” is a silly song, but it’s an extraordinary track.

The greatness of “When The Levee Breaks” as a track is established in its first five seconds, opening with one of the all-time great drum breaks in recorded history. John Bonham is playing a tight groove, but it’s the recording and production that make it so awesome and majestic:

• The drums were recorded in a stairwell in Headley Grange with incredible natural reverb. Engineer Andy Johns had the bright idea to put the kit at the bottom of the stairs, and to put the mics halfway up a flight of stairs above it.
• The recording is compressed to within an inch of its life, and it is run through a perfectly timed single-tap slapback delay from a Binson Echorec.
• The tape is slowed down, which gives it that sludgy timbre.

It’s no wonder that the break has been sampled a million times. It’s also no wonder that people are more likely to sample the track than to try to cover the song.

Like John Bonham’s drums, Robert Plant’s harmonica benefits from superb production too. They recorded the harmonica part in a space with cavernous natural reverb (possibly a fireplace?), ran the recording through trippy reverse tape echo, and then slowed it down. You could play any nonsense through that processing and it would sound epic.

Zeppelin had a tough time recording the song before they tried it at Headley Grange, and they only played it live a couple of times afterwards. Without that specific sonic environment and that specific signal processing, the song doesn’t work. Led Zeppelin may not have always had good judgment in their uses of the blues, but they definitely knew how to get a great sound on tape.

Update: Marc Weidenbaum drew my attention to a recent live performance of “When The Levee” Breaks” by Robert Plant, it’s a good one.

I saw this Robert Plant show here in S.F. back in 2019, from essentially this video's angle, but further back. I loved his band's arrangements. The video's sound, sadly, doesn't do it justice. Had a "Celtic chamber trip-hop" quality to it.https://t.co/bUfyESzyDF

— Marc Weidenbaum (@disquiet) July 22, 2022