The general form of the song consist of a repeated A section, each with alterations to instrumentation and to melody. Each section however is similar in terms of melodic basis, all using the Eb major blues scale to base the melody; Eb. Gb, Ab, Bbb, Bb, Db; and each using the same deviation of the 12 bar blues. This consists of I, I, I, I7, IV, IV, I, I, V, V, I, V, the V at the end is an alteration to the original 12 bar blues which would finish on the tonic, yet this dominant chord allows the music to feel circular as it returns to the tonic at the next playing of the 12 bar blues. This circular motion allows each section to expand upon themes/motifs that the previous section plays, as each new A section is given to a different solo instrument, showing this era as the beginning of the striving virtuoso musicians within jazz. A1 is the trumpet solo section, where it begins with an anacrusis in order for Armstrong to establish a new tempo amongst the other performers. This then begins with the rising motif found in the first bar; F# quaver to a G semiquaver to Bb semibreve tied to a crotchet. The first note of an F# is the minor 3rd in this key’s blue scale, immediately establishing the music as a blues influenced piece. This then moves chromatically to the G which moves effectively into the Bb chord note that is next played; this semitone step creates a gentle movement to the Bb which is the fifth of the Eb chord that is being played at this point. This is the basis for the piece as each instrument manipulates this pattern and plays with the melody surrounding it as each musician improvises around this original idea, such as the later trumpet solo which plays a this progression but extends the Bb. Underneath each solo instrument the piano underpins the music by playing the 12 bar harmonic chords on a straight crotchet rhythm, contrasting against the interesting and often syncopated rhythms of the melody.
Section A2 is given to the trombone soloist and the accompaniment now also includes a percussive instrument which sounds similar to horse hooves, adding a swung rhythm to the music giving interesting rhythmic counterpoint and this also adds to the slightly lethargic feel that the music has to go along with the “blues” feel. The trombone also adds an interesting new timbre to the music as it uses multiple slides and sounds slightly muted. Moving to section A3 and now the soloist is the vocalist Louis Armstrong, instead of using lyrics however he uses his voice like an instrument and ‘scats’, meaning his voice is still an instrument and he can still be considered as a virtuoso musician as he improvises throughout. This improvisation is still based around the 12-bar blues progression and the Eb blues scale, being able to improvise with his voice in this way shows the beauty of Armstrong’s melodies, his phrasing and ability to find melodies that compliment the clarinet. The vocals are accompanied by a clarinet in this A3 section to thicken the texture of the deviated 12-bar blues progression and give a new fuller timbre to the music to show progression.
Section A4 is the only section which deviates from the 12-bar blues progression that has been used up to this point, the piano is the soloist at this point and so it must deviate from the progression it has been playing. It still begins on Eb to retain the key centre and still in the first bar it moves to Eb over Db, then in bar 2 Eb over C then Bb7 giving a descending bass line as the piano then moves to Eb over Bb; A over Ab then a straight movement from Ab to A to Bb, contrasting with an ascent to show the music is still developing. Armstrong again experiments with dynamics at this point, using a mixture of legato and staccato to contrast against one another and keep the music interesting and innovative.
In section A5 the soloist is again the trumpet, but this time the melody is entirely different to that of section A1 as this time it begins with a note held for a full 4 bars, this long note creates tension and excitement as this is now the last section of the movement and any musician able to hold a note that long on a trumpet is a truly skilled and experienced performer. This is followed by a descending four note semiquaver motif made up of all of the flats used thus far; Bb, Ab, Gb and Eb. At this point Armstrong experiments with inflection as each playing of this motif varies; the first time it is played straight, the second time the first note is delayed. This pulls the tempo back slightly, yet this is then contrasted against with the third playing which is straight again, then the fourth playing sees the first note delayed again. Differently to previous sections the solo instrument changes, as at bar 9 the piano again takes over for a short period before the trumpet returns at bar 12. This gives a conversation-like effect as if the musicians are discussing through their instruments that the end has come. At bar 12 the trumpet returns and finishes the song creating a full circle.
This song is mainly based upon the same 12-bar blues progression that is stated at the beginning in section A1; from there soloists are able to shine in their own sections that are improvised. This music was the beginning of the virtuoso musicians and led the way for improvisational yet scored music.
