Katy Perry - Firework

Lyrics can be found here.

YouTube video here.

Music by Mikkel Eriksen, Katy Perry, Tor Eric Hermansen, Esther Dean, and Sandy Wilhelm

KEY: Ab Major

TIME: 4/4

TEMPO: 124

VERSES

As seen in the illustration above, the chord progressions for first three verses are I-bVII-vi-IV. The '9' in Db(9) is sort of an anticipation of the Eb in the following Ab major chord (colored red). While there is no dominant chord until the bridge, the Eb serves a significant role throughout the song as a ciphering tone strengthening unity among key progressions. The illustration below shows the slightly altered chord progression for verses 4,5, and 6. The bVII is substituted with a ii chord.

PRE-CHORUS

The eight bars before the chorus section is labeled as "pre-chorus" in my sheet music I purchased. While it has a slightly altered chord progression from the previous verse section, the main purpose of the pre-chorus is to transfer the vocals to a higher tessitura. The blue notes in the illustration above are the main notes in the vocal line. The vocal line is an ascending Ab major scale starting on C. As mentioned earlier, the Eb plays a significant role here as well. The Eb is a chord tone of Ab and Fm7. However, it is held through the Bbm7 and Db chords. Therefore, Bbm7 and Db have a '4' and a '9' indicating it contains the non-chord tone Eb.

CHORUS

The chorus contains the same chord progression as the pre-chorus. The melody always lands on a non-chord tone on the downbeat, and the melody doesn't really rest on the tonic Ab throughout the chorus. The Bb in the second bar of the illustration above is a non-chord tone that serves as an appoggiatura because it resolves downward to the Ab in the third beat. The C in the third bar is anticipated in the previous bar and becomes an unresolved suspension. The same idea is repeated in the fourth and fifth bars.

BRIDGE

There is a short eight bar bridge in the song which doesn't modulate and remains in the key of Ab. The familiar vi7, IV with a scale degree 2, and I are used. In addition to these chords we have a dominant chord appear for the first and only time in the song.