Jazz improvisation
Melodic variation and playing by ear
### Melodic variation and playing by ear

From the [dixieland](/wiki/Dixieland "Dixieland") era through to the [swing music](/wiki/Swing_music "Swing music") era, many solo performers improvised by varying and embellishing the existing melody of a song and by [playing by ear](/wiki/Playing_by_ear "Playing by ear") over the chord changes using well\-known [riffs](/wiki/Riff "Riff"). While this approach worked well during these musical eras, given that the [chord progressions](/wiki/Chord_progression "Chord progression") were simpler and used less [modulation](/wiki/Modulation "Modulation") to unusual keys, with the development of [bebop](/wiki/Bebop "Bebop") in the 1940s, the embellishment and "playing by ear" approach was no longer enough.

Although swing was designed for dancing, bebop was not. Bebop used complex chord progressions, unusual [altered chords](/wiki/Altered_chord "Altered chord") and [extended chords](/wiki/Extended_chord "Extended chord"), and extensive modulations, including to remote keys that are not closely related to the [tonic key](/wiki/Tonic_key "Tonic key") (the main key or home key of a song). Whereas Dixieland and swing tunes might have one chord change every two bars with some sections with one chord change per bar, bebop tunes often had two chord changes per bar with many changing key every four bars. In addition, since bebop was for listening rather than dancing, the tempo was not constrained by danceability; bebop tunes were often faster than those of the swing era.

With bebop's complex tunes and chords and fast tempo, melodic embellishments and playing by ear were no longer sufficient to enable performers to improvise effectively. Saxophone player [Charlie Parker](/wiki/Charlie_Parker "Charlie Parker") began to solo by using scales associated with the chords, including altered extensions such as flattened ninths, sharpened elevenths and flattened thirteenths, and by using the chord tones and themselves as a framework for the creation of [chromatic](/wiki/Chromatic_scale "Chromatic scale") improvisation.


What scales did saxophonist Charlie Parker use when soloing?