An experience of modal jazz needs awareness of musical modes. In bebop an in hard bop, musicians use chords to supply the background for solos. A song starts out with a theme that introduces the chords for the solos. These chords repeat across the full song, while the soloists play new, improvised themes over the repeated chord progression. By the 1950s, improvising over chords had make such a dominant part of jazz, that sidemen at recording dates were occasionally given nothing less than an inventory of chords to play from. Towards the end of the 1950s, spurred by the experiments of composer and bandleader George Russell, musicians started to use a modal approach.
They selected not to pen their pieces using conventional chord changes, but instead using modal scales. As an effect of this call, the bass guitar player, for example, doesn't have to 'walk ' from one significant chord tone to that of another to make each chord change sound, as is the case in standard bebop or hard bop compositions ; rather, she is free to improvise bass lines inside a particular mode. In modal jazz, bass lines are frequently built in 4 or 8 bar phrases with a stress of the root or the 5th degree on beat one of such phrases. In a similar fashion , the comping instrument isn't limited to play the standard chord voicings of the bop lexicon, but instead can play chord voicings based on differing pitch combos from the parent mode. The way soloists made solos changed a lot with the appearance of modal jazz. In bebop, a soloist usually constructs solos to fit inside a specific set of chord changes. In modal jazz, with its shortage of standard bop chord changes, the soloist can create interest by exploring the specific mode in rhythmically and melodically sundry ways.