INSIDE THE MUSIC

Key: A Harmonic language: Blues I7 IV7 V7 Tempo: ≈170bpm

Novel features: Metric fake-out; (Unintended) Syncopation; Tresillo and Double Tresillo grouping dissonance; Metric and rhythmic diminution.

Led Zep IV’s second track shares the key, harmonic language and many of the stylistic features of Black Dog, but again subverts them with some sophisticated rhythmic and metric devices. These don’t include the irregular bars found in Black Dog (although there is the illusion of one), but they still create some challenges to the listener despite the familiar context.

The first is the most infamous (and for many it’s quite bewildering), John Bonham’s solo drum intro. The playing is neither overly complex nor abstract, but it has tripped up countless listeners, publishers and even professional musicians in the last 50 years.

Here is the issue: we hear from the outset a rapid and syncopated drum groove, but it is steady and accessible with a clear pulse and meter. However, when we get to the end of the fourth bar, and where we would expect a big pay off on the start of the fifth bar, we get what sounds like an extra beat and a half (or three eighth-notes) before the guitars and bass enter confidently. Is this section actually four and three-eighths bars long? Listeners tolerate (or shrug off) this surplus rhythm by conceptualising it, as many publishers do, as four bars of 4/4 and one bar of 3/8.

Fig 1: A common mishearing – and (ludicrous) Fig 2: Bonham’s internalised conception of transcription – of the intro to Rock And Roll the Rock And Roll intro

This sort of dissonance that occurs at the beginning of a track is termed ‘initiating dissonance’, or more colourfully ‘metric fake-out’, where our presumptions about the prevailing meter are thwarted. These are quite common, since we are yet to build a predictive grid in which to understand our rhythms, and musicians even deviously construct such traps.

However, in this case there is no intended sabotage. When the drums start we naturally assume it to be the first beat in the bar (and this interpretation is supported by the strong first hit). It is, however, a three subdivision ‘upbeat’ preceding the first bar. In this interpretation everything falls into place (see Figure 2), like an optical illusion flipping.

If you’ve not heard it this way before, then it can take some tries. But one way to lock in this hearing is to match it to Chuck Berry’s guitar intro to Johnny B. Goode, which maps to the rhythm very closely – and may well be the inspiration to Bonham’s into (given the song title). This mishearing is a by-product of starting with solo drums, and Bonham’s musical choice of using an upbeat and syncopation, not a ‘muso’ deception.

Another interesting device in Rock And Roll occurs on the structural level. The entire track here is essentially a standard blues form. After the drum intro we hear a 12-bar blues in A, which is used for instrumental breaks throughout the track. What happens elsewhere in the verse-chorus sections is exactly the same form except it is stretched to double its length. If a chord lasts two bars previously, it now lasts four bars, and so on, in a process known as ‘rhythmic augmentation’, which is an inventive way of creating structural variation from limited material.

In spite of these devices the track is strictly 4/4 throughout, but one other spice is added within this backdrop: ‘grouping dissonance’ occurs when two or more musical layers disagree in how rhythmic structures are grouped. There are countless ways this can be done, but perhaps the most common in rock (and in fact all global music based on dance forms) is known as the tresillo, which is when eight rhythmic units are subdivided into groups of 3 + 3 + 2 (= 8). This momentarily implies a grouping of three before surrendering to the binary landmark. A spicier version (used, incidentally, in Led Zeppelin’s Kashmir) is known as the double tresillo. This is where the groups of three hold out even longer before relinquishing to the next ‘binary landmark’ of 16 (3 + 3 + 3 + 3

+ 2 + 2) creating a greater rhythmic itch.

Fig 3: tresillo and double tresillo patterns.

The chorus break of Rock And Roll savours these devices, using a tresillo (with each hit starting with the word ‘been’) immediately followed by a double tresillo (with hits starting with ‘lone(ly)’). They each last two bars, which means that the 16-unit double tresillo has to run through its sequence twice as fast as the eight-unit tresillo. This rhythmic ‘crunching’ is known as ‘rhythmic diminution’, a mirror – and microcosm – of what occurs with the 12- and 24-bar blues forms.

The tresillo-(accelerated) double tresillo rhythmic framework in the chorus break of Rock And Roll.