“Improvisation isn’t a matter of just making any ol’ thing up. Jazz, like any language, has its own grammar and vocabulary. There’s no right or wrong, just some choices that are better than others,” observed trum- peter Wynton Marsalis famously.

Shane Cooper knows what he means. For the past decade, the 27-year-old bassist has been mainlining an improvisational vocabulary that courses through Ornette Coleman’s harmolodics and Charlie Mingus’ freewheeling Third Stream swing back to Bird’s bebop and before. He’s honed his chops as a sideman for S.A. jazz giants such as saxophonist Zim Ngqawana, trumpeter Feya Faku, and drummer Louis Moholo-Moholo. He’s strutted his lightning-fast reflexes in hip young Mother City combos including Afro-Indo modal fusionists Babu, hard-bop heads The Restless Natives, pianist Kyle Shepherd’s trio, and guitarist Reza Khota’s quartet.

It’s this collaborative language honed through years of rigorous live performance that drives his compositional choices on his debut album as a leader. “Jazz is all about interpretation and personality, so I focused on my favourite elements of the musicians’ styles, and tied them together so we could expand on the songs as a unit,” says Cooper about Oscillations. It’s this kaleidoscope of personalities in conversation that take flight on opener “Broken Blues”, where the harmolodic groove cooked up by Kesivan Naidoo (drums), Bokani Dyer (piano, Rhodes), Reza Khota (guitar), Justin Bellairs (alto sax), Buddy Wells (tenor sax) and Cooper confirms what audiences already knew about him – that he is the most lyrical of contemporary S.A. jazz bassists.

But whereas the lyricism of a Johnny Dyani at his most ecstatic seemed hellbent on bursting open the gates of delirium, Cooper’s lyricism is sculpted toward more subtle, collective lines of flight. Listen to “Destination Unknown”, where Cooper staples his groove onto Bellairs’ “sheets of sound” saxophone squalls, creating an addictively arrhythmic counterpoint to Dyer’s pastoral piano textures and Khoza’s electric guitar runs.

Of course, in any killer jazz combo, regardless of solo virtuosity, the centre of creative gravity is invariably an axis between the leader and the drummer. So who better than an explosive skinsman like Naidoo to pave the path for the chamber jazz and progressive rock conversations of “Shadowplay”? It’s Cooper and Naidoo’s own shadowplay that kickstarts hard-bop conversation in swing, “Oriah” and elevates “The Herdsman” from just another Cape jazzy ballad into an elegiac ECM epic. It’s these oscillations – between subtle S.A. jazz shades and a distinctly global aesthetic – that Carlo Mombelli’s nuanced production gives just enough space to swing in the silences.