Bebop Scale
A scale used in modern jazz, formed by adding a chromatic passing tone to a seven-note scale.
What it means
The bebop scale is a family of eight-note scales used in modern jazz, formed from seven-note scales such as major, minor, or Mixolydian by inserting an extra chromatic passing tone. The best known is the dominant bebop scale, which adds a chromatic note between the minor and major seventh of the Mixolydian scale.
The added eighth note shifts the rhythmic pattern: running the scale in even eighth notes causes the chord tones to land again on the strong beats.
Musical use
Bebop scales grew out of the improvisational practice of 1940s bebop musicians, who used them to play smooth, chord-consistent eighth-note runs over fast-moving harmony without distorting the harmonic sense. Alongside the dominant bebop scale there are correspondingly built variants over major and minor chords.
It should be distinguished from the chromatic scale, which includes all twelve semitones equally, whereas the bebop scale adds only one deliberately placed chromatic passing tone to an otherwise diatonic scale.
Performance practice
Practice the bebop scale first in even eighth notes ascending and descending to feel how the passing tone steers chord tones onto the strong beats. Use it deliberately over the matching chords of a piece rather than running it mechanically across the whole form.