CITAR – Catholic University of Porto; ESMAE – IPP
Jazz Harmony: Chordscales and Implied Modulatory Fields
In mainstream jazz tradition, when an improviser or perhaps even an arranger faces a lead sheet – typically containing the lyrics, melody and chord progression of a song – his job is to translate every chord symbol into a chordscale, which will then be used to extemporaneously produce melodies that outline the harmonic surface in a convincing manner.
In tonal jazz, a chordscale is a defining mode, that unifies each passing chord with the prevailing key. Once the harmonic function of the basic chord structure1 is understood – diatonic, secondary dominant, modal interchange (mixture), etc. – it is necessary to infer the remaining pitches in order to typically obtain the chordscale. These remaining pitches have multiple chromatic possibilities originating different chordscale options, which imparts jazz its polymodal idiosyncrasy reminiscent of the blues tradition.
A strong, well-informed artist should comprehend the effects of his/her creative choices. Therefore, from an analytical standpoint, it is essential to examine how different chordscales contribute to shape the intensity curve of a jazz solo. In one of the earliest studies in chordscale theory, George Russell proposed a system of categorizing chordscales, according to their tonal gravity in relation to a Lydian tonic. In my opinion the system has its merits but generally fails to highlight tonal relations.
I will propose a method of categorization based on the degree of tonal ambiguity and consequently harmonic tension between each chordscale and the prevailing key based on the implied resolution of the pitch-classes it contains. Excerpts of transcriptions and recordings from standard repertoire will be presented and analyzed as a mean to illustrate key concepts.
Keywords: Chordscale, Improvisation
Paulo Perfeito, trombonista, compositor e pedagogo – nasceu na cidade do Porto em 1974. Doctor of Musical Arts – Eastman School of Music ‘17, Master of Music – New England Conservatory ‘07 e Bachelor of Music – Berklee College of Music ‘01. Professor adjunto na ESMAE – IPP e investigador integrado no CITAR – UCP. Na sua atividade de investigador destaca-se o trabalho XXth C. Compositional Techniques Applied to Jazz: Pitch- Class Sets in Jazz Composition and Improvisation apresentado na EuroMAC 2017 – Estrasburgo, França e GATM 2017 – Rimini, Italia. Foi premiado com o DownBeat Student Music Award em 2013, Marian McPartland Scholarship, Fulbright Scholarship, Herb Pomeroy Award for Outstanding Jazz Composer and Arranger e a Bolsa Jovens Criadores do Centro Nacional de Cultura. Colabora/ou com a Orquestra de Jazz de Matosinhos, Casa da Música, Universidade de Aveiro, Academia de Música de Espinho. Lidera a Nu Jazz Orchestra e o 6teto Paulo Perfeito.