The name Blue Note Records calls to mind a once-regnant sound in jazz: the hard-bop of the 1950s and ’60s, with its springy four-beat swing rhythm, its spare-but-lush horn harmonies, its flinty, percussive piano playing. Imagine a smoky room with a horn player blowing fiercely over a strolling standup bass, and you’re hearing the Blue Note sound. Think of a modernist, cobalt-hued album cover, with blocky title text and a photo of a studious young musician hunkered over an instrument, and you’re envisioning the Blue Note look.

It’s been a long time since that fantasy was a reality — for jazz or for Blue Note , which turns 80 this year. Since the 1960s, the label has been through numerous corporate mergers, partial shutdowns and creative readjustments, all while working to keep pace with shifts that have left jazz in a state of diffusion: Much of its forward motion is happening on the fringes, and there’s hardly a mainstream sound to speak of.

“Jazz” today encompasses an entire ocean of post-collegiate musical work: highbrow traditionalism, renegade funk, droning free improvisations. Jazz musicians now have to be improvisers deeply trained in the American tradition, with roots in the blues. Beyond that, almost anything goes.