Michael Gibbs

Progressive big band is a post–World War II evolution of big band jazz that shifts the focus from dance music to concert-oriented, highly arranged works. It preserves the massed brass-and-reeds power of swing-era ensembles, but adopts bebop’s advanced harmony and lines, classical orchestration techniques, and ambitious, often through-composed forms. Arrangers favored expanded instrumentation (French horns, tuba, Latin percussion, sometimes strings), dense voicings, polytonality, and dramatic dynamic contrasts, yielding a bold, modernist “concert jazz” sound. Compared with swing, the rhythm can alternate between a hard-driving 4/4, even-eighth feels, Latin grooves, and unusual meters, while sections trade contrapuntal lines more than riff-based call-and-response. The result is an epic, sometimes imposing aesthetic that bridged jazz and contemporary classical ideas.

Gnawa is a spiritual, trance-based music of Morocco associated with the Gnawa brotherhoods, a community with roots in sub‑Saharan Africa and Sufi Islam. It centers on a deep, percussive bass lute called the guembri (also known as sintir or hajhuj), the bright metallic clatter of iron castanets (qraqeb/krakebs), unison handclaps, and call‑and‑response vocals. Performances often unfold in an all‑night ritual called a lila (derdeba), where cyclical 6/8 grooves and repetitive chants invite communal participation and induce a trance state. The repertoire invokes saints and ancestral spirits (mluk), moving through color-coded suites and intensifying rhythmic layers. While firmly rooted in West African rhythmic sensibilities, Gnawa also absorbs Maghrebi and Sufi aesthetics, producing a sound that is both devotional and intensely groove‑driven.