3.3. Chordgram Completion for Analysis and Improvisation

Determining the missing tones of a chord in order to reconstruct its generating scale is the object of chordscale analysis. Understanding chordscales is a necessary step in mastering melodic improvisation, which is an essential feature of several prominent popular styles, such as Jazz, Bossa Nova, Rock, and many Latin genres.

A careful chordscale analysis typically requires transcribing the tones from the chord symbol to a regular staff, then filling the gaps between tones and adjusting accidents, according to the melodic context and the stylistic preferences. For example, if the chord has a major 3^rd , Jazz improvisers generally assume that the scale contains an augmented 4^th , while Rock musicians tend to favor the perfect 4^th , used mainly as a passing tone. 

It turns out that chordgram notation is a natural born tool for chordscale analysis. With chordgrams, the analysis can be made “in place”, without the need of an auxiliary staff, because the inference of the missing chord tones can be graphically attained, by filling the chordgram blank labels. Such operation is denominated chordgram completion.

In principle, chordgram completion can be performed by the musicians on their own parts, during the rehearsals or even at the backstage, minutes before a live concert. Since chordgrams are practically fixed-size symbols, no extra space is needed in the sheet for the analysis.

After completion, a chordgram becomes an extremely compact – but also clear and explicit – representation of a scale. With some training, it is possible to play the scale by reading it directly in the chordgram – a very powerful tool for improvisation practice.