If you are not a musician but have wondered what on earth is going on in the music when you listen to traditional jazz bands, you may be interested to know the musicians have to follow a ground plan in every performance.
At its simplest this may be nothing more than playing an eight-bar melody, with its accompanying chord sequence over and over, with various improvisations, sometimes by soloists and sometimes involving full ensemble. There may also be a few bars of Introduction and there may be a Tag or a Coda (a little tail added to the end of the final chorus); but these are not essential.
For an example, listen to Tuba Skinny playing ‘Jet Black Blues’. They do nothing more than work through the same eight bars FIFTEEN times, but with so much creativity that the performance is always interesting:
The same applies to standard 12-bar blues, in which there is a single theme.
When we play the popular tunes of the 1920s and 1930s, the familiar song, usually called the Chorus, often consists of 32 bars, so the ground plan may be: just play that Chorus without any additional material straight through, several times – to allow for solos and ensemble work.
Sometimes the song has a good Verse (often 16 bars), so the plan may be to work through the Verse once before embarking of several treatments of the Chorus – perhaps returning once more to the Verse before finishing.
But with more complex structures, notably the classically-composed tunes of the 1920s, you often find two or more themes – each a little melody in itself and each with its own chord structure.
Often there is a key change, too. So a composition by King Oliver or Clarence Williams or Jelly Roll Morton may be structured like this:
INTRODUCTION : Usually two or four bars.
THEME A : Usually 16 or 32 bars.
THEME B : Usually 16 or 32 bars.
BRIDGE (A short linking, transitional passage, often leading to a key change).
THEME C : Usually 32 bars.
It often happens that the band agrees to play Theme A twice and then Theme B twice and then Theme A once more before tackling the Bridge. (This is also a very common procedure with classic rags written before 1920.) After that, they may remain on Theme C, playing it several times, with various improvisations. They will probably end with an Ensemble Chorus and perhaps a Coda.
Of course, this pattern can be varied in many ways. For example, a band may choose to play a number of solo choruses on Theme B, before playing the Bridge.
These structural patterns can be traced back to such classical composers as Haydn and Mozart. Well into the Nineteenth Century such an ichnography found its way into brass band music and eventually into ragtime structures. Theme C (usually involving the key change) was often called ‘The Trio’ in classical music and was still labelled as such in the sheet music of popular tunes in the early Twentieth Century. Even today it is sometimes still called the Trio by practising musicians.
If all this makes little sense to you, let me give you a practical example. Have a look at Tuba Skinny playing ‘Cushion Foot Stomp’ and let me talk you through their performance. I am referring to this video:
This is a Clarence Williams composition with three themes. Here's how this performance is structured.
(1) EIGHT-BAR INTRODUCTION : 03 seconds - 13 seconds.
(2) THEME A (standard 12-bar) : 14 secs. - 29 secs. Craig leading with the main melody.
(3) THEME B (24 bars) : Todd leading, with Shaye 'decorating' : 30 secs. - 1 min. 01 secs.
(4) THEME B (24 bars) : Craig leading, with Shaye 'decorating’ : 1 min. 02 secs - 1 min. 33 secs.
(5) THEME A (the 12-bar again) : 1 min. 34 secs. - 1 min. 49 secs.
(6) BRIDGE (4 bars, leading into Key Change - Key has been E flat until now but is about to become A flat) : 1 min. 50 secs - 1 min. 54 secs.
(7) THEME C - Classically known as the TRIO. This is the Main Theme on which the piece settles, and is to be used as the basis for improvised solos. (16 bars in Ab, always with a ‘break’ on Bars 7 and 8) : Taken by Craig: 1 min. 55 secs – 2 mins. 16 secs. (You can hear his ‘break’ at 2 mins. 04 secs. - 2 mins. 05 secs.)
(8) THEME C : Taken by Barnabus and including the ‘break’ - 2 mins. 17 secs – 2 mins. 37 secs.
(9) THEME C : Taken by Shaye and including the ‘break’ - 2 mins. 38 secs – 2 mins. 59 secs.
(10) THEME C : Taken by Max and including the ‘break’ - 3 mins. 00 secs – 3 mins. 19 secs.
(11) THEME C : Taken by Todd and including the ‘break’ - 3 mins. 20 secs – 3 mins. 41 secs.
(12) THEME C : Taken by Robin and including the ‘break’ - 3 mins. 42 secs – 4 mins. 02 secs.
(13) THEME C : Taken by the full ensemble but with the ‘break’ allocated to Todd - 4 mins. 03 secs – 4 mins. 23 secs.
(14) CODA (4 bars) : Initiated by Robin – 4 mins. 24 secs – 4 mins. 30 secs.
For a performance to come out as slickly as this, all band members have to remember the agreed ichnography as well as the three principal melodies and the chord progressions.