As smaller ensemble soloists became increasingly hungry for new improvisational directives, some players sought to venture beyond Western adaptation of major and minor scales. Drawing from medieval church modes, which used altered intervals between common tones, players found new inspiration. Soloists could now free themselves from the restrictions of dominant keys and shift the tonal centers to form new harmonics within their playing.
This became especially useful with pianists and guitarists, as well as trumpet and sax players. Pianist Bill Evans is noted for his Modal approach.